By the second section the dimensions to which the Canal and locks shall be enlarged, on Tuesday, the 20th day of October next, to hear the report of the engineers, and consider further of this subject. On the 6th day of July the Board of Ca tions: Company's shops. Both of these gentle-as the Canal Board may be of the opinion|'adjourns, will adjourn to meet at this place men were, for many years, in the service that the public interest requires such imof the Company, in the Department of maprovement. chinery, before they became contractors; and to them, together with the late PHINEAS DAVIS, the former contractor, is to be attributed the perfection of the present loco-are to be determined by the Canal Board; nal Commissioners at a meeting held in the motive. Their establishment is a large one, and the third section authorizes an indepen-city of Albany adopted the following resoluemploying upwards of an hundred work- dent Canal to be constructed in passing men, and of itself is of great benefit through cities and villages, and at other places, inthe employment that it gives, and the mostead of enlarging the present works, if the ney which, necessarily, it is the means of Canal Board shall decide that the public incirculating. The Company has a prior claim to the services of the contractors, payterest will be thereby promoted. ing a stipulative price for the engines, ($5000,) and the machinery which are obtained from them, and paying for repairs by the time which they consume. The expenses of the shops are borne by the con tractors, who build and manufacture for others as well as the Company. The shops and permanent machinery have cost the Company about $10,000,-which sum has been already returned to it in the reduced price for which the contractors build the engines, in consideration of the advantages of the use of the shops, the proximity to the road, and the opportunities of working for other companies. The first meeting of the Canal Board under said act was held at the Canal Room in the Comptroller's office, in the city of Albany, on the 20th day of June last. On the third day of July the Board adopted the following resolutions: 1. Resolved, That the public interest requires the enlargement and improvement of the Erie Canal, and the construction of a double set of lift locks therein. 2. Resolved, That the doubling of the locks, and the works connected therewith, ought to be commenced without delay, and prosecuted with all reasonable diligence, beginning with that portion of the Canal between the village of Syracuse and the city of Albany. a sufficient sum shall have been collected Resolved, That, for the purpose of making the survey of the improvement of the Erie Canal as contemplated by a resolution of the Canal Board of the 3d inst., said survey shall be commenced at the following places: at the city of Albany, and proceed west; at the upper lock in the village of Frankfort, and proceed east; at the upper lock in the village of Frankfort, and proceed west; and at Buffalo and proceed cast. Resolved, That the charge of the survey commencing at Albany and proceeding west, is confided to the charge of John B. Jervis: That the charge of the survey commencing at Frankfort and proceeding east, is confided to Nathan S. Roberts: That the charge of the survey commencing at Frankfort and proceeding west, is confided to Frederick C. Mills, and that the survey commencing at Buffalo and proceeding east, is confided to Holmes Hutchinson. Each of whom is hereby appointed and designated as the engineer for the purpose aforesaid. At a meeting of the Board of Canal Commissioners, held at Utica on the 17th day of July, the following, regulations were adopted in reference to the surveys of the Erie Canal, with a view to its enlarge In the annual report of the Baltimore and Ohio Railroad Company, the power of their engines has frequently been mentioned, and the authority and character of these reports have been quite sufficient to authenticate 3. Resolved, Pursuant to the 10th section the facts therein stated. Your Con.mittee of said act, that the enlargement of the Caare aware, however, that the incredulous nal should be commenced immediately after as to the ascent of the plains at Parr's Spring Ridge, have not been few, and, perhaps, the very importance of the results stated, so far exceeding all previous experience, has been the cause of doubt; or in other words, "the news was held to be too good 4. Resolved, That the Canal Commis-ment. to be true." Your Committee, however, are sioners proceed without delay to make sur- 1st. The surveys shall be of such a dewitnesses, with many others, to the surprising efforts and efficiency of the engines in veys for all the improvements contem-scription as will enable the engineers to requestion, and they are glad that an oppor. plated by the said act, and that they make port the probable comparative expense and tunity has been afforded them to add their the necessary appropriation of all lands, opposing obstacles of enlarging the Canal testimony in corroboration of that which waters, and streams for the purpose aforereflects so much credit upon the mechanics| said. of our country, and to express their approbation of the persevering and patriotic individuals who, in ihe management of the Bal timore and Ohio Railroad, have called our native talent into play, and done so much All of which is respectfully submitted. 5. Resolved, That the Canal be enlarged so as to give six feet depth of water, and in general sixty feet width of water on the surface, with a slope of two feet to one in the banks. 6. Resolved, That the locks be enlarged First Branch. Committee of the REPORT OF THE CANAL BOARD, UNDER THE CANAL. To the Legislature of the State of New-York: REPORT: 7. Resolved, That the aqueducts be constructed, so as to give at least forty feet water way, except that the Rochester aqueduct may, in the discretion of the Canal Commissioners, be constructed with a water-way not less than thirty-six feet wide. 8. Resolved, That in other respects than those provided for by the foregoing resolutions, the Canal Commissioners make such improvements in the Canal and the works Connected with the same, as they shall deem expedient. 9. Resolved, That the Canal Commissioners be requested to cause such examinations and estimates to be made as the time will permit, for the purpose of ascertaining the practicability and probable expense of an enlargement of the Canal, so The first section of this act authorizes as to give the several sizes of six and seven and directs the Canal Commissioners to feet depth of water: the width at surface enlarge and improve the Erie Canal, and to be in general ten times the depth of water. construct a double set of lift locks, as soon 10. Resolved, That the Board, when it to 6 feet deep and 60 feet wide, and also 7 feet deep and 70 feet wide: said report to be made by the 20th of October next, or at an earlier day if practicable. 2d. At all difficult and expensive points, such as the perpendicular bluff of rocks east of the three locks below Schenectady, at Flint Hill, at the bluff of rocks below the two locks at Philip's, at Yankee Hill, at the bluff above Fultonville, at the little and big nose, at Dieffendorf's hill, at the Little Falls opposite Herkimer, at the Cayuga marshes, at the Irondequoit, Sandy creek, Otter creek, and Fish creek embankments, and from Lockport to Buffalo the width may be limited to 50 feet. 3d. The quautity of water to be appropriated shall be sufficient to supply the maximum amount of business which can be done on the enlarged Canal, calculating 150 cubic feet per minute per mile for the eastern section, and 100 cubic feet per minute per mile on the middle and western sections, for a Canal of the dimensions of the present Erie Canal, to which is to be added the lockage ROME SUMMIT. A feeder from the Mohawk river, from the Black river, and Fish creek, and the Canaseraga creek. JORDAN SUMMIT. In presenting this estimate it is proper to To report on the expediency of making remark, that it is not contemplated to cona reservoir of the Skaneateles lake, either by struct a double set of lift locks on the enraising the water or cutting down the out-larged plan, until the business on the canal let, and also of making a reservoir of the shall be so increased as to render it necesOwasco Lake and a feeder from the Owasco sary, excepting in situations where the precreek. sent locks require to be rebuilt, or where in making the enlargement the line is so changed as to render the present locks useless. A feeder from the Genesee river and the Tonawanta and Oak Orchard creeks. 5th. The Engineers shall furnish tnemselves with convenient transcripts of the These estimates include the expense of map made by Holmes Hutchinson under removing buildings from the line, but nothe statute directing the survey of the Ca-thing for damages. nals designating there on the exterior The estimate from Utica to Lyons, is bounds of the survey made by Mr. Hutchin-not confined to the expense of the enlargeson for doubling the locks. 6th. A berm shall be formed at all places except where deep rock excavations occur, and the drainage water shall be conducted under the Canal by culverts, or into it by regular sluices, formed for that purpose with a cess pool outside the bounds of the Canal to receive the deposit. ment and the necessary additional feeders, These estimates were made during the past season, when the streams of the country were much above their ordinary minimum flow; but deductions, proper in the opinion of the engineer, were made from the guaged quantity on this account. The examinations show that a much larger quantity of water is available for the Rome and Jordan summits, than the largest canal which has been contemplated will require, for the extent of business which can be done with double locks. 7th. The banks to be raised 3 feet above the surface of water on the inner edge, and 2 feet on the outer edge, and the towing path bank to be 12 feet wide on the top, with slopes on each side of two feet horizon- These improvements to the canal are tal base to every foot rise; and the berm necessary, even though it were not enlarg- On the western section it is expected bank is to be 8 feet wide on the top with the ed. If the amount estimated for this pur- that the principal supply for the canal must same slopes. pose and such part of the expense for feed- be drawn from Lake Erie, and it is intended 8th. In cities and villages where the Ca-ers and reservoirs as may not be required to give the canal such capacity as will rennal cannot be widened to the required width were deducted, it would redure the aggre-der this practicable, without creating a curwithout removing buildings at a great ex-gate which has been presented, but how rent which may impede the navigation. pense, examinations shall be made for a much cannot now readily be determined. The surveys have shown that additional The plans on which the estimates are feeders may be taken from the Mohawk based, are of the most substantial charac- river, and there can be no doubt about obter, comprising much better and more ex-taining a supply for the eastern section. pensive work than the plans on which the Erie canal was originally constructed. The locks will cost nearly 100 per cent. more. separate Canal. 9th. As far as practicable the pound reaches between the locks shall be so large that two lockages of water shall not depress the surface more than six inches. 10th. The engineers are requested to report plans for bridges having a water way of 50 and 60 feet under them. 11th. To examine and report on the question how far the new lock can be most conveniently located from the present lock, in reference to the convenience of navigation. 12th. To report on the expediency of making the towing path of sufficient width to enable two horses to tow abreast. 13th. To report such suggestions as may occur to them, in reference to the duties submitted to their charge. 14th. To report an opinion of the dimensions of a lock best adapted to economy in transportation, in reference to the enlarged canal on either plan. The Canal Board at their meeting in October, reconsidered the decision made in July, in reference to the extent of the enlargement of the canal and locks. These estimates were, no doubt, made with all practicable care and correctness; The Board, after a careful examination but it is difficult to speak of them with much of the information derived from the surveys, certainty. Great allowances should be and the facts submitted to their considera made, on account of the short time allotted tion, decided that the canal should be en for this service, and the difficulty of esti-larged to seven feet depth of water, and 70 mating the value of work, which must be feet width of surface; and in the present done under circumstances like those attend-month, they agreed on a lock 110 feet long ing the improvement in question. between the quoin posts, and 18 feet width of chamber. On the basis which was furnished in the directions to the engineers, it is estimated that the enlarged canal will require an additional quantity of 14,546 cubic feet of water per minute for the Rome summit, and 7,990 cubic feet per minute for the Jordan summit. This computation is made on 250 lockages, every twenty-four hours, for the Rome summit, and 220 for the Jordan summit. The engineers completed the surveys, and their reports were submitted to the Canal Board on the 20th day of October, with estimates of the cost of the contem- The additional feeders and reservoirs plated improvement on both plans for the which have been surveyed, and which are enlargement, and of all the feeders and re- available to supply these summits, are estiservoirs directed to be surveyed. These re-mated to furnish as follows: ports and estimates are herewith submitted. The aggregate of the estimates including FOR THE ROME SUMMIT. the cost of a double set of lift locks on the From the Black river, cubic feet 14,681 To decide on the dimensions to which the canal and locks shall be enlarged, has imposed a question of high responsibility, not free from doubt, and about which there is some diversity of opinion. To change the boundaries of the canal, imposes a delicate interference with private property; and the Canal Board are aware that in fixing on the limits to which the canal should be enlarged, they were deciding a question which should be considered definitely settled. The idea of disturbing the bounds of the canal for a second enlargement cannot be entertained. The prospective, business, and every consideration connected with this subject, unequivocally indicated, that the enlargement of the canal and locks should be such as 13,725 would furnish the greatest facilities to busi ness, and the cheapest rate of transporta- || tables, the water passes by a short canal out, or removed after the whole of the water tion.' ato a larger basin, called the muant, along is evaporated to dryness. In the former case wo sides of which are arranged a number the salt is tolerably pure, in the latter it is of smaller ones, in two rows, called the bitter and disagreeable; nor could it be adtreas. These have floors of clay or plais-vantageously disposed of, were it not that the er impervious to water. Canals are form- use of it is compelled in countries where salt ed in such manner that each leads the water is a government monopoly. The object of from the muant towards the common corner the complex arrangement of canals and baof four of the areas, but is still separated sins, as we have described it, is, that when rom them by their surrounding dykes. A the operation is in regular train, the water, temporary communication being made with in its passage from the reservoir to the areas these canals, the water is permitted to flow where the evaporation is completed, shall expose a large surface to the air, and at the same time have such a degree of motion as may bring it regularly in contact with fresh air. The arrangement of a set of salt pans may be understood from the annexed plate. The amount of cargo which approaches nearest the maximum that can be transported on a canal, with the greatest economy, experience has no where pointed out with certainty. The Commissioners here refer to various experiments to determine the relative proportion of the transverse section of a boat and canal, in reference to the power of traction. Such different data have been used in making the calculations, that they dis-upon the areas to the depth of about an inch, agree materially. (To be continued.) Applications of Chemistry to the Useful Arts, being the substance of a Course of Lectures delivered in Columbia College, New-York, by James Renwick, Professor of Natural Experimental Philosophy and Chemistry. III. SALTS OF COMMERCE. 1. COMMON SALT. The sources whence common salt, (chloride of sodium,) is derived, are, the water of the ocean; salt springs, which are found issuing from certain geological formations; and beds of rock salt. The two former may be separated from the salt they hold in solution, either by spontaneous or by artificial evaporation. MANUFACTURE OF SALT FROM SEA-WATER The salt raked out of the arcas is piled on the neighboring ground in pyramidal heaps, where it is permitted to drain, in order to separate the water which adheres, with such matter as it holds in solution, and it attracts water from the air, which dissolves a certain soluble and deliquescent substance which, as we shall see, is contained in sea-water. These heaps are thatched with straw or bushes, in order to prevent the entrance of rain. DUMAS. Chimic appliquee aux arts. There are some warm and dry climates where, from these favorable circumstances, salt is formed by spontaneous evaporation from natural basins, which have an occasional communication with the sea at the highest state of the tides. From such basins it is only necessary to rake out the salt as it forms from time to time at the surface. In less favorable climates, artificial salt- Ch pans are formed by embanking portions of salt meadow, and dividing the embanked space, by dykes, into a number of basins, into which the water being successively admitted, and caused to expose a large surface, is finally evaporated. The first basin is of considerable size, and serves as a reservoir, receiving water from the ocean at spring tides, and retaining it for use. From this reservoir the salt water is conveyed into the first of a series of rectangular ba-he reservoir and the beds. sins, called beds, by a tube laid under ground. This tube enters at the corner of the first bed, and is directed by the arrangement of the openings in the separating The salt manufactured by spontaneous dykes, diagonally across each of them to It is proper tl at the pans should be placed evaporation, even under the most favora the end of the series. From the last bed it in such manner as to receive most advan- ble circumstances, is not as pure as some is passed by another subterranean tube in- tageously the currents of the principal winds. other descriptions, but has the advantage of to an open canal, which is directed in such In the north of Europe the use of such being formed in regular cubic crystals, a manner as nearly to enclose a square. salt pans begins early in March, and may which makes it better fitted for keeping The tube is admitted at one of the angles of continue until the end of September. The meat and curing fish than any other descripthis square, and the channel drawn from it water which is first admitted into the areas, tion. Such salt is imported into this counaround the square until it comes again into remains for eight days before it is com- try in large quantities from Spain and Pora basin, which is separated from the first pletely evaporated. The next charge will tugal, from Turk's Island, and the Cape de branch of the canal by a dyke. This ba-ke a less time, for the water in the beds, Verds. A large natural salt pan also exsin is the first of a second series, of the tables, &c., will have been somewhat con- ists within our own territory at Key West. same extent as the first series, which go centrated; and at the height of the season, by the name of tables. After traversing the the areas may be changed daily. gg, subterranean communication between hh, do. between the beds and canal. The impurities of which we have spoken are contained in sea-water, and are but par Common salt, 2.54-72. Chloride of magnesium, 0.35-10. Sulphate of magnesia, tially separated in the process, or the sub-creases, a further separation takes place,||tion. Here it loses about 25 per cent. of sequent draining. In 100 pts. by weight until the liquid becomes highly concentraits weight by drainage. The salt is then of sea-water, there are dissolved about 3 1-2 ed, and the soluble matter may be obtain-of a fine grain, white color, and agreeable of solid matter. This matter, obtained ed at a small expense of fuel by artificial taste. The coarse or bay-salt, which is formed in by rapid evaporation to dryness, is com- evaporation. This method is used in the northern and eastern parts of Siberia, but large crystals by spontaneous evaporation, posed of the salt obtained is of inferior quality,-al-is best suited, as has already been stated, though not necessarily so, were the process for curing neat, in the dry way, and parskillfully conducted. ticularly for packing fish. In the latter process, the cavities whence the entrails of the fish have been removed, are filled with the salt, and the barrels are filled with alternate layers of salt and fish. The only solvent is the liquor which exudes from the fish, and it appears that the more slowly this is drawn off by the salt the better. The der this process too rapid. capillary attraction of fine salt would ren Carbonates of lime and magnesia, Sulphate of lime, 0.58-16. .02-00.67 3.50 100. of But the salt of Note-Both of the above methods are practicable in the northern and eastern parts of the United States. Our summers and autumns would give us at least six months of weather in which the evaporation Of these substances, the carbonates of by exposure to the sun and air might be lime and magnesia being held in solution successfully practised, and if our spring be by excess of acid, will be deposited in warm those of the south of Europe, this is more less advantageous for the purpose than weather in consequence of the escape than compensated by the superior dryness the acid when a large surface is exposed to and steadiness of our autumnal climate. the air. The sulphate of lime being but Our winters, also, equal in cold those of the sparingly soluble, will, after the few first same latitude in eastern Asia, and the me- therefore, to whom the fisheries are a most days of the process, be left behind in the thod of congelation might no doubt be ap- important object of national industry, subtables, &c., before the water reaches the plied to advantage. Salt is manufactured ject the imported bay-salt to a process of areas. It will also determine the converon the shores of Massachusetts Bay, but purification. sion of a part of the sulphate of magnesia we are under the impression that the evapointo sulphate of soda; the latter will uniteration is performed by artificial heat. with the sulphate of lime to form a double salt. The remaining sulphate of magnesia, having a solubility in cold water about one half more than that of common salt, but MANUFACTURE OF SALT FROM SEA-WATER Spain and Portugal, and still more of For this purpose, it is dissolved in seawater, and evaporated at a moderate heat; the evaporation being rendered more slow by covering the large shallow pans of sheetiron in which it is heated, with planks. This manufacture is generally conducted It is to the great care that is taken in the being not much more than one-fifth in quan- on a small scale, and with little skill, and preparation of this salt that the very supetity, will not begin to crystalize until more it is only under peculiar circumstances that rior quality of the fish cured by the Dutch than six-sevenths of the water which re- it has been profitably pursued. Thus the is, in a great degree, owing. They also mains after the salt begins to crystalize is fishermen of the shores of Scotland are per- kill and clean the fish the instant it is evaporated. Up to this time, then, the salt, mitted to use salt manufactured on the spot, caught, on which account it is better than if well drained, would be nearly pure. The free from the heavy excise with which it that which is permitted to die in consechloride of magnesium is deliquescent and is loaded in other parts of the kingdom. It In the curing of meat, also, it cannot be highly soluble; it will therefore not begin appears probable that their art consists in quence of a change of element. to crystalize until after the sulphate of mag- little more than evaporating salt water al- questioned that the method of rubbing and nesia, and the discharge of the water that most to dryness in iron kettles, for the pro-packing in dry salt in large crystals is much to be preferred to steeping in a pickle preremains after the first appearance of the duct obtained is extremely impure. bitter taste of the sulphate in the salt, will A tolerably pure salt is manufactured in pared by dissolving salt. which the north of France from sea-water, carry off both, except what adhere memay chanically to the crystals. Even if a part has been filtered through sand that has been of the chloride of magnesium have been thrown up by the sea beyond the usual reach formed in the solid state, it may of the tides, and which is also within reach of the spray. As the water evaporates rated in consequence of its deliquescence, from this, it remains charged with various mitting the salt to drain. be sepa SALT FROM SALT SPRINGS. AUTHORITY. DUMAS. Traite de Chimic. More attention has been paid to the manufacture of common salt from salt springs, by scientific men, than to any other of the by virtue of which it will attract moisture! The liquid, after sources whence this article has been obfrom the atmosphere, and this moisture will proportions of solid salt. passing through the sand, usually has a tained. The salts obtained by analysis also dissolve some of the sulphate of mag- density of 1.14, but sometimes as much as from several springs are, besides the chlonesia. This moisture is separated by per-1.17. It is evaporated in leader vessels, ride of sodium, chloride of magnesium, suland boiled rapidly over a wood fire. The phate of magnesia, carbonate of lime, and Together So far as mechanical impurities adhering liquid rises into froth, and must be continu-sometimes carbonate of iron. to the crystals are concerned, the salt formally stirred to prevent it from boiling over. they make up abont 16-1000th parts of the ed in large crystals by spontaneous evapo- The surface is occasionally cooled by throw weight of the water of the spring of Mouration, is superior to all others, for it will expose a less surface under equal weight.ng on cold brine, in order that a scum tiers, and are in the following proportions, which forms may be skimmed off, until the with the exception of the carbonate of iron, These impurities, if deliquescent, will be salt begins to crystalize. The evaporation which is deposited as soon as the water is also much more easily removed. is continued until the whole of the water is exposed to the air : The best salt manufactured in this man-driven off, the solid deposit being continu Carbonate of lime, ner contains 95 per cent. of chloride of sodium, while that made at an unfavorable ally stirred, in order to prevent the lead of Sulphate of lime, 0.05 per ct. 3.125 0.27 16.875 the boiler from melting. The salt thus obseason has not more than four fifths of its tained is in fine powder, but is still very imweight of true marine salt, and upwards of pure. In order to separate the soluble im-Chloride of sodium, 7 per cent. of sulphate of magnesia. MANUFACTURE OF SALT FROM SEA-WATER BY CONGELATION. purities, the salt is put into baskets, which are suspended over the boilers while the succeeding evaporation is going on. It is thus exposed to the action of a large quanWhen water holding but little common tity of steam, which penetrating between salt in solution, is exposed to a temperature the crystals is condensed, and dissolves the below freezing, the water is separated into deliquescent impurities along with other two parts, one of which is nearly pure, and soluble matters, and a portion of common passes into the state of ice, the other re- salt. The salt is then permitted to drain mains liquid and retains the whole of the by placing it on a floor covered with sand, salt in solution. As the temperature de-whence the salt has been obtained by filtra These waters, as well as those of the sea, contain also the iodides and bromides of magnesium. Rationale. When the process of boiling this water is followed with attention, it is found that one fourth part of the water has been evaporated and the density increased to 1.14, before the sulphate of lime begins In the method of cords, the water is made to trickle over ropes stretched in a vertical direction from the upper beams of an open frame building to a basin which receives it beneath. to be deposited. The deposit then gradu-||buted in greatest abundance on the wind-||is rapidly boiled and concentrated until the ally increases until 5-6ths of the water has ward side. The water having fallen over salt begins to crystalize; and during this been evaporated, after which it begins to one series of hurdles, is again pumped operation, the greater part of the double diminish, and when 17-20ths of the water up and falls over another series in the same sulphate of lime and soda is deposited. As has been evaporated, ceases altogether. building, until it has descended nine or ten the liquid wastes, more brine is added, which The deposit, when examined, is composed times. is also freed from this sulphate, and the of sulphate of lime and sulphate of soda, in boiling and addition of brine are continued nearly equal proportions, forming in fact a until the vessel is filled with brine of the double salt, and nearly as much common density of 1.23. In the next vessel the salt as of both united. At a density of evaporation is conducted by a gentle heat, 1.23, when abont 9-10ths of the water has the liquid being barely kept at a boiling tembeen evaporated, common salt begins to In the method of tables, a number of shal-perature, and as the salt forms at the surcrystalize at the surface, if the action of the low wooden troughs are arranged in a lofty face, it is removed by rakes, until it manifire be moderate; if not, it will also be building. Each of these is inclined suffi- fests signs of the presence of the bitter sulprecipitated. The salt which crystalizes ciently to allow the water to run gently phate and chloride. At or previous to this first is nearly pure, but gradually becomes over its surface, to the lower end, where it epoch, lime might be added, and the quanless so, and is finally affected by a bitter passes to the trough beneath, whose incli-tity of salt obtained would be increased.. taste, arising from the sulphate of magne nation is in the opposite direction, and thus sia. If the evaporation be stopped as soon in succession till it reaches the bottom. as this taste becomes sensible, there remains In either of these ways, the water is a thick viscid liquid containing a portion of brought to a density of 1.14; about 9-10ths common salt, along with chloride of mag-of its original quantity being evaporated. nesium, sulphate of soda, and the iodides It is then conducted to large reservoirs, and bromides of magnesium. A farther where it deposits the insoluble matters quantity of common salt may be obtained which were mixed with it. The mother waters, which remain after the salt becomes impure, are set aside, and permitted to stand over a winter, exposed to the influence of frost. At a low temperature the sulphate of magnesia is decomposed by chloride of sodium, and sulphate of soda results. The several substances in the mother water form three successive deposits, of which sulphate of soda is the last, and the only one of any value. A section of a building containing hur dles, for the purpose of concentrating water holding salt in solution, by spontaneous evaporation, with a part of the machinery, is represented in the annexed plate. PLATE II. even from this, by the aid of lime. This Artificial heat is next employed. The Process.-The mode of obtaining salt from the salt springs of the continent of Enrope is in strict conformity to the principles. deduced from the preceding observations. About 9-10ths of the water, of the density of 1.01, are usually evaporated by exposure to air. This spontaneous evaporation is performed in three different ways, by that of hurdles; that of tables; and that of cords. The advantages of these are nearly equal, if we have regard to the quantity and quality of the salt, and the rate at which it is crystalized; the only consideration then is their relative cost in different places. In the first method, hurdles or bundles of twigs of a thorny shrub are piled in open frame buildings covered by a roof. The water is pumped up to the top of these buildings and then distributed in small streams upon the upper course of the bundles of twigs. The direction of these buildings is such that the principal prevailing winds may be at right angles to their length; and the gutters which convey the water are so formed, that it may be distri a, a, a, frame. d, d, d, piles of hurdles. h તારી e, main channel for the brine. g, open space for the circulation of air. a plank is applied cut into similar and simlarly situated notches. These planks are caused to slide along the side of the main channel, and, according to their position, nay close the notches altogether, leave them partially or wholly open. P, P, inclined planes to catch the brine as it falls from the ends of the hurdles. r, reservoir. s, s, s, piles which serve as foundation. t, t, steps to ascend to the inclined planes. At one of the European establishments, the spontaneous evaporation is carried farther during the summer months. For this purpose, a building is constructed about |