put into a hot press with a daily change of cloths, until it is properly set; it is then dried in the air and made up into the various articles you see before you.

A large factory was fitted up near Manchester for the manufacture of lactite, but I am informed that up to the present time it has not been a financial success, for the articles which have been made, such as buttons, &c., when sewn on to clothes, have the unpleasant property of readily breaking in pieces on the slightest touch, or often on none at all; so I cannot see how lactite buttons handles, &c. can compete with the time-honoured and well-tried bone articles. Still there are cases when the skim milk has to be thrown away; at such times it may be profitable to make lactite, and it may be an industry for the British farmer, who is at present sorely tried with severe competition. This lactite when well prepared will keep for any length of time.

The second process which I have been experimenting with is to convert the skim milk or whey into a portable article of food; for since, as is well known, it is impossible to send skim milk or whey at a profit to distant towns, some simple process by which the farmers could get rid of the water at a small cost and leave a residue rich in nitrogenous matter is a thing very much to be desired. The specimens which I place before you have been made from skim milk and whey. The name given to this new compound is lactoserin. This is prepared in a variety of ways as food for man, cattle, and poultry :

No. 1 is dry curds, not ground.

No. 2, the same, but ground to fine powder.

No. 3, serin. This consists chiefly of milk sugar from the evaporated whey.

No. 4, lactoserin, which consists of one-third of skim milk, two-thirds whey.

No. 5, double lactoserin, half skim milk, half whey.

No. 6, brown roasted lactoserin, for mixing with cocoa instead of starch. I have not had time to make analyses of all these preparations, but I think it will be sufficient if I give one the mean of several analyses :

Double Lactoserine.

Water....

Protein matters

Fat

Carbohydrates...

Ash

Mr. GRIMSHAW thought cattle would be more likely to take kindly to whey than human beings.

Mr. J. CARTER BELL said the process was invented by Wm. Rehnström, of Sweden (this Journal, 1892, 933).

Mr. CRIPPIN said he should like to volunteer a word on this point. He had had the misfortune to lose 98 calves about two years and a half ago and had had to give up milk since. The milk trade was a very peculiar one in certain districts. In some it was a very good one and in others not so good, and in some cases instead of sending milk to market they made butter and cheese, and so forth. It was then that they met with a difficulty as to getting rid of the surplus skim milk and whey they had to dispose of. Pigs and cattle required careful treatment, and he did not think they would flourish on a diet of pure whey or skim milk. In order to keep pigs successfully they wanted to be near a good hotel where they keep a good swill tub, In feeding them with skim milk they must add a little meal, and he thought that was a subject upon which chemists might assist poor unfortunate farmers out of their difficulty. He did not think that there was any farmer at the present time, even if he had a good homestead, who was making money, and the further utilisation of skim milk would be very advantageous to farmers' interests.

Nottingham Section.

UNIVERSITY COLLEGE, NOTTINGHAM.

The manufacture of these products ought to possess great interest for the English farmer, for it will enable him to turn to marketable value what has too often been a waste product. This manufacture of dry curds and serin can be carried on at smail places as well as large, but I need not say that it would be more economical to work 1,000 gallons than 100.

The dry curds are obtained from the skim milk in quite the same way as in the production of cheese, by putting rennet into it. The curds are pressed and ground, and then dried in a drying oven.

It has been estimated that the manufacture of the dry eurds will not cost more than about one farthing a gallon for the skim milk used.

The serin is manufactured by evaporating skim milk and whey together in different proportions for different purposes. For this purpose a special evaporating vessel is required which will hold about 250 gallons; this costs in Sweden (where the process is being worked) 557., and a machine for the stirring up the mass as it is cooling down. This apparatus will cost 10l. for the size corresponding to the 250 gallons. The expense in Sweden is only one farthing a gallon, therefore the cheapness and simplicity of the process ought to recommend itself to the attention of our agriculturists at home.

DISCUSSION.

The CHAIRMAN said that the paper dealt with a useful application of a waste product. The utilisation of skim milk and whey for the purposes of food would certainly be more appreciated than when used in the manufacture of door knobs, electric bell furniture, and handles for walking sticks.

C. H. Field.

H. Forth.

F. D. Mordle.

S. J. Pentecost.

Chairman: L. Archbutt. Vice-Chairman: F. Clowes.

Committee:

H. J. Staples.

C. Taylor.

Sir John Turney.

G. J. Ward.

J. T. Wood.

Treasurer: J. M. C. Paton.

Hon. Local Secretary:

R. L. Whiteley, University College, Nottingham.

Notices of Papers and Communications for the Meetings to be sent to the Local Secretary.

SESSION 1892-98.

Meeting held Wednesday, December 14th, 1892.

MR. L. ARCHBUTT IN THE CHAIR.

THE USE OF "CHEMICAL" LEAD.

BY F. J. R. CARULLA.

THERE are few more surprising changes of their kind than some met with by the chemist when he leaves the experi1 mental operations of the laboratory for those of an industrial character in the works. Where he has used glass and porcelain on the small scale he has now to employ metals when working on a commercial scale, and of these lead will be the chief if engaged in the manufacture of sulphuric acid or with processes that require its employment.

Liebig has well said that without cork, platinum, glass, and caoutchouc, "we might have made some progress (in

chemical investigations), but it would have been slow; we might have accomplished much, but it would have been far less than has been done with their aid." It may, with equal truth, be said that without lead chemical industry would have made little progress, seeing how intimately it is bound up with the production of sulphuric acid and how unsuccessful have been the attempts to find substitutes for a metal so soft that it can be eroded and perforated by insects, but which has proved nevertheless very useful.

Widespread though chemical knowledge has become anyone may yet be excused for ignorance on the importance of lead to the industrial chemist when even such an exhaustive work as Percy's classical treatise dismisses the subject in half a dozen lines, mentioning only its application to sulphuric acid chambers. Other authors are still more brief and some do not even refer to the chemical use of this metal, as is the case, for example, in what is also an excellent book, viz., "The Useful Metals and their Alloys," published so late as 1866, a time when already immense quantities of lead had been employed to carry on numerous processes of chemical manufacture.

The quantity of lead used in the construction of sulphuric acid chambers is no doubt very large, yet there are works where this acid is manufactured in which the very considerable yearly outlay for this metal includes few items for their repair. Although wear and tear is certain they may yet be so slow as hardly to be felt, except when the time arrives for the complete renewal of the chambers. The concentrating pans for bringing up the strength of chamber acid to that of brown oil of vitriol where towers are not employed, and the saturators where the manufacture of sulphate of ammonia is carried on may be found, although making less show, to give in the long run greater employment to the lead mills than the chambers do.

The chemist who takes up manufacturing operations may very naturally imagine that for him the term "chemical lead requires no definition, and it may be a surprise for him to read that: "In the North of England those rolling mills which roll the sheet lead for the many large vitriol works supply a special kind of "chemical lead," which is made from the melted-up old chamber lead, pipes, &c.; in this case many impurities, especially antimony from "regulus valves, &c., get into the lead, which seems to improve its quality for acid chambers" (Lunge's "Sulphuric Acid," 1879, Edition, p. 42). The supposition that chemical lead should be a very pure article would therefore not appear correct, although the contrary opinion has also been stoutly maintained.

It was not originally intended to discuss in this paper the interesting point as to what impurities, if any, improve lead for the various purposes to which it is applied by the manufacturing chemist, yet, as the subject has undergone a most painstaking and laborious investigation at the hands of Professor Lunge and Mr. Ernst Schmid, the details of which have just been published in the Journal of the Germau Society of Chemical Industry (Zeit. f. angew. Chem. 1892, 21-22), a few of the results arrived at may not be thought out of place here.

It should be premised that upwards of a thousand tests were made by Mr. Schmid, daring a period extending over two years, on various kinds of lead, the chief of which yielded the following on analysis:

Hard lead.....................

Cu 0.05, Bi 0.01, Sb 1'81, As 0:10, Fe 0'01, Sn 0'04 per cent.

Antimonial lead.... Cu 9'1 to 0:3, Sb. 18'1 to 15 3. As 1 to 3'1 Sn 0.1 per cent. (not homogeneous).

The concentrated acids employed in these investigations were non-nitrous sulphuric acid of 1·84 sp. gr. and nitrous vitriol of the same strength with 1 per cent. of N2O3.

Diluted acids were also used, ranging from 1.725 to 1.765 sp. gr., that is to say of the strength of BOV.

The main and most important conclusions arrived at by Dr. Lunge from a consideration of the tabulated results are-1st. That the purest soft lead is the most suitable material for the construction of apparatus to be employed

in the manufacture of sulphuric acid, such as chambers, cisterns, towers, and the like. This is also the case with concentrating pans, at all events, when these are so arranged that the heat is not first directed under the pan containing the strongest acid, so that the temperature may never, even for a short time, rise above 200° C. 2nd. The presence of 0.2 per cent. of antimony in the lead is not injurious. With cold acid it is certain that the corrosive action is not so strong on such an alloy as it is on soft purer lead. This, however, only holds good with cold acid, and if the percentage of antimony exceed 0.2 the antimonial lead is attacked much more vigorously than is the soft lead, and the action increases enormously as the temperature rises. The use of antimonial lead for concentrating pans is therefore specially to be guarded against. 3rd. The presence of copper, which lead will only take up to the extent of 0.2 per cent. so as to form a homogeneous alloy, at temperatures under the boiling point of water has little or no effect on the action of vitriol on the lead. At 200° C. its protective action is just perceptible, but as higher temperatures are reached the presence of this small percentage of copper is a decided protection to the lead from that sudden attack by the hot acid to which the presence of any bismuth in the lead makes it so liable.

As no doubt a full abstract of Dr. Lunge's interesting paper will appear in due course in our Journal, it is the less necessary to give here more than the important results above described. These suffice to show that "chemical" lead should be the purest that can be made, but a special quality, with 01 to 0.2 per cent. of copper for exceptional purposes when very hot acid has to be dealt with, might be manufactured. As the admixture of this special lead when sent back as scrap would not injure the ordinary chemical lead, there is no obvious reason why the lead mills should not avail themselves of this new knowledge, and adopt the suggested course at once.

at

In the main the matter is left very much as the scientific chemist would expect to find it, namely, that the purer the lead, the less easy it is for acids to act upon it, and important as is the exceptional result obtained abnormally high temperatures when the lead is alloyed with a small percentage of copper, we can still suppose that the physical conditions of its employment may also deserve consideration. The question is not an idle one:-Can the life of any apparatus made of this metal be lengthened by changing or modifying any of the conditions under which it is at present employed?

Covering in the passages between the various acid chambers so as to protect them from the weather not only makes the lead last longer but prevents the dilution of the chamber acid that must occur in rainy weather, however carefully the water may be led away, when they are placed in the open. In this connection the writer remembers no treat like that afforded him by one of our worthy VicePresidents, Mr. Crowder, when taken over the works so well managed by that gentleman. The numerous passages between the chambers were covered over and so clean that in the subdued light they looked more like the long aisles of some ancient temple than like portions of a chemical works. It was no surprise to learn that a woman-a veritable "chambermaid "-periodically swept them. can be imagined that chambers so well kept-apart from their preservation-must materially contribute to the comfort of everyone engaged about them, and thus tend to increase the efficiency of the works.

It

It is difficult to think of any other metal that is employed under such comparatively severe conditions as lead is, by the chemical manufacturer. The concentration of sulphuric acid in lead pans is an operation that may well make the man stand aghast who is accustomed to ample "factors of safety." When it is considered that the boiling point of the strong acid is about 338° C., whilst the melting point of lead, variously given as from 262° to 334° C., is generally accepted as 322 C. (= 612° F.), it will be obvious that the slightest oversight in allowing the concentration to be carried too far in the leaden pan must bring about its destruction. The acid made in the chambers is thus converted into brown acid of about 1.74 sp. gr. The heat seldom rising above 150° C., but the small margin for

It is plain that as the pans rest on cast-iron plates placed over the flues and fireplace, imprudence or inattention may land the attendant in a serious difficulty. The acid may get up to strength whilst the fire is still in the furnace, and the flues are still hot, making it unsafe to empty the pan, whilst at the same time a certain element of danger arises if the acid be left in the lead pan, because under the supposed conditions concentration will continue. Of course

a careful and experienced man safeguards himself by due attention against such an occurrence, but the possible dilemma is worth mentioning as on one occasion when the demand for acid was urgent, a well-meaning, but none the less rash foreman destroyed a pan by emptying it whilst the flues were too hot, well aware of what the result might be. His excuse was urgency. Such action may well be compared to that of a man, who being on the top of a tower,

=

1 ft.

should throw himself to the bottom, instead of carefully descending by the stairs because he happened to be called down in haste.

The iron plates making up the platform that covers the fireplace and flues, are usually plain open sand castings, about a foot wide and an inch thick. They are placed edge to edge so as to make as level a surface as may be. It is easy to understand, however, that with the distortion that will in the course of time occur through unequal heating, which cannot be avoided, the sharp corners of the iron plates will at some places rise above the general surface, and constitute a danger for the lead. This is frequently guarded against by placing thin hoop iron over the joints, but the writer has adopted with success the plan of rounding the corners of the smooth side of the open sand plates (Fig. 2). This in no way adds to the cost of the castings, whilst it

also distinguishes their smooth side, so that on looking over a completed bed one need have no doubt as to whether any plate has been put the right way up. The V-shaped space left between each pair of plates may remain open without detriment of any kind if the radius of the curved corner be not too large. inch has been found a convenient radius.

The fact that the linear expansion of lead is between two and three times that of iron, introduces a difficulty in such a combination as we are considering that soon makes itself obvious by the puckered character, that the bottoms of the lead pans assume especially when the actual difference between the expansion of the two metals is accentuated by great length. Iron expands 0.00118 of its length when raised from the freezing to the boiling point of water, whilst lead will expand as much as 0.00301 of its length under the same circumstances. This means that

with a pan, say 28 feet long, whilst the expansion of the iron bed or platform will only be a little over inch, the expansion of the lead will actually exceed one inch, a dimension that will be considerably added to by the further increase of temperature when acid is being concentrated. Indeed at the higher temperatures the difference between the two expansions will be more than one inch. This addition to the length of the pan must be taken up somewhere, and in the case supposed would show itself by a number of transverse puckers or folds, dividing the bottom of the pan as it were into a number of shallow compart

ments.

In the case of a very long pan it would appear possible to take up this extra expansion by corrugating the surface of the iron plates (Fig. 3). The lead as it expanded would by the mere weight of superincumbent acid bend itself in place,

although the distance between the corrugations in relation to the thickness of the lead would be an important factor in the success of the experiment, as if too great the weight of the acid would be certain to cause extension of the lead long before the heat expanded it to the required dimensions for bedding it completely. Such a plan judiciously carried out must, one would think, be in any case beneficial, as the expansion would be taken up evenly all over the length of

the bottom of the pan instead of by irregular folds at chance intervals, as happens with the ordinary level bed. The lead would not be strained so severely as is now the case, a point of some importance when it is remembered that the tenacity of lead which is 2 kilos. per sq. millimetre between 15° and 20° C., becomes reduced to 0.54 kilos. at 100° C., and must be still more largely reduced at the higher temperatures with which we have to deal.

C

be true that on the next contraction occurring the lead would now bed itself fairly over the whole surface of the iron, but as we are seeking to do this when the apparatus is hot, and not when it is cold, there is no advantage in bringing about this state of affairs. How little such a condition of things would help us may be inferred from the fact that taking gold as the standard and calling its conducting power 1000, the conducting power of copper for heat is 898.2, that of iron is 374 3, and that of lead is only 179.6. The danger would therefore arise by the superposition of lead in the manner supposed that it might become over-heated where this metal came in contact with the iron in the concave part of the corrugations where the iron is thinnest. The thin

parts of the iron would not only give up their own heat to the lead, but would receive the heat from the thicker sections and convey that also to the lead. This concentration of heat at intervals with such a bad conductor as lead might constitute a serious danger.

It was, in fact, the risk that constantly exists, even with the ordinary flat cast-iron bed, of getting those portions over and near the fire dangerously hot that led the writer to devise the plan, for which provisional protection has been cbtained, of inserting some good conductor, such as copper, between the lead and the iron, sandwiching it, as it were, in order to more evenly distribute the heat (Fig. 5). For this purpose gold of course would be the ideal metal, and though

silver is not far behind the nobler metal in its conducting power for heat, still it is to be feared that, notwithstanding the complaints of the bi-metallists, it is hardly yet cheap enough for using under lead pans. Copper then, very little below silver in its efficiency, must be selected as a conductor to take away any excess of heat from a dangerously hot place to some cooler part where it can be safely and advantageously employed. The conducting power of copper for heat compared with that of lead being, as has just been stated, 898 2: 179 6, it will be obvious, especially when taking into account that the corresponding figure for iron is 374 3, that a sudden access of heat from any particular portion of the iron surface will be more quickly spread over a large area than could be the case with the lead alone in contact with the iron.

It hardly needs demonstrating that the great conductivity of the copper presents no element of danger, still it is possible to object, that as this metal allows the heat to pass through it so readily, the lead might be imperilled. But, sandwiched between the iron and the lead as the copper finds itself, this metal can receive no more heat than that which the iron imparts, and this is exactly the same amount that the lead would be offered were the copper away. As, however, the copper readily conducts away the heat presented to its under surface laterally as well as through its thickness, it must be clear that any over-heated place in the iron cannot be so dangerous to the lead when the copper is interposed as if the lead were in actual contact with the hot iron.

As the linear expansion of copper when heated between 0° C. and 100° C. is 6 00172 of its length, a figure that is nearly a mean between that of lead and of iron, the arrangement above explained reduces, if not quite by half, yet in a considerable degree the great difference in the dilation that occurs between the two metals in contact when the lead pan is placed directly on the iron bed. The greater elasticity and tenacity of copper as compared with

lead would also permit the use of the corrugated surface previously discussed, and which was shown to be impracticable with the ordinary plan of placing the lead pans directly on the iron. The greater elasticity and tenacity of the copper would, though in the form of a thin sheet, enable it to return to its flat position when cold, carrying up with it the lead from the hollows of the corrugations, again adapting itself to these concavities, when once more the metals might be subjected to heat.

The writer has now under observation a pan 6 ft. by 6 ft. placed over a pyrites burner with a plate of copper in. interposed between the plain iron platform and the bottom of the lead pan. The result in regard to the equal distribution of heat over the whole area of the pan is all that was anticipated or that could be desired, the temperature hardly varying one degree between the points that are exposed to the greatest and to the least heat. The interposition of the copper also seems in no way to diminish the efficiency of the apparatus as an evaporator. In point of fact it works so well that there is some difficulty in preventing the belief from gaining ground that the heat has actually increased!

The even distribution of heat proves that the desired object has been attained, and that the lead pan is thoroughly protected from those places in the iron bed where there is an excess of heat. At some future time it may be possible to bring before you results of working that cannot as yet be given, the apparatus having been completed and set to work only a few days ago.

It may be mentioned that the presence of any solid matter with the acid on the bottom of concentrating pans constitutes a serious danger. A piece of slate that may have accidentally dropped in or some crystalline accretion, however formed, that may prevent the acid from conveying away the heat may cause a local overheating that will destroy the pan. Such events should not be frequent; in fact, there is no reason why, with proper working, they

should ever happen, but as they have occurred it is pleasant to think that the inserted copper plate would certainly afford a measure of protection in such cases.

The lead pans being all of one piece made from a single sheet, as has been above explained, require no autogenous soldering or burning. It is best, if possible, to replace them altogether when requiring repairs than to have them patched. Should this, however, from any cause be necessary, it is well to make sure that the lead strips used by the plumbers are actual lead and not some kind of solder. It is difficult to make some people realise that the strength of a chain is only that of its weakest link.

The lead saturators, in which sulphate of ammonia is produced, also require considerable care in management, although the heat in them is largely generated within the liquor they contain. The ammonia-gas coming from the still is led into the sulphuric acid with which the saturators are charged with considerable local evolution of heat. Brown oil of vitriol is usually employed by works that do not make acid, but chamber acid may be found strong enough to answer the purpose when this is available. The use of rectified vitriol would be wasteful in the extreme, nevertheless a dearth of other acid may justify its employment rather than bring operations to a standstill. It may appear superfluous to add that when such a contingency occurs it should be seen that the acid does not enter the saturator anywhere near the lead. Indeed the best plan would be to dilute it with due precautions before passing it into the saturator. The caution, however, may be worth noting, for the writer once saw a hole thus produced some 6 in. by 4 in. in lead in. thick, a result that might have been expected by anyone who considered the great heat evolved when concentrated acid is diluted.

In Mr. Levinstein's admirable address to the Manchester Section of our Society, printed in the number of the Journal just to hand, great stress is laid on the importance of technical schools to impart practical knowledge to students to direct manufacturing who may subsequently have operations. Whilst not minimising in the least the advantages to be derived from such a course, one may point out that there is an equal if not greater necessity for working men, the actual producers, to acquire a knowledge of the elementary principles of science. The want of this frequently leads to the most prejudicial waste and damage to their employers, and of course indirectly to themselves. Certainly it may happen that if a workman tries to ascertain the temperature of an acid by floating his thermometer and reading it as if he were taking the specific gravity of the liquid, the incident may be more likely to raise a smile than cause grief at the time, but on reflection it will be admitted that much damage must occur from ignorance of an analogous character in other directions.

A knowledge of geometrical rules and figures may not appear so important to the man who has to use lead as to the worker in iron, the disposition to feel that lead scrap is worth very nearly as much as the new lead being always present. None the less it may be a real misfortune to cut lead to waste on some occasions, and when a man has to rip open a new leaden scoop formed of parallelograms and triangles in order to make another like it the benefit that would accrue iu his case from a better knowledge of geometry is very apparent. As this knowledge is equally useful to the girl who has to cut out a dress from the piece, or to her who spends her time in fancy work, as to the man who has to shape a piece of wood or metal, one may be permitted to express the opinion that practical geometry (not Euclid) should form a branch of elementary education and be taught to every boy and girl in the land.

This might go hand-in-hand with free-hand drawing the universal teaching of which has also been advocated, bnt desirable as efficiency in this art may be, in the opinion of the writer it is far below geometrical knowledge for practice purposes. The inaccurate measurements frequently given by men who one would think might be trusted encourages the belief that a little geometrical training in their younger days might have made them more reliable. industry is so intimately bound up with the mechanical arts whose very essence is geometry, that it may be inferred a more general knowledge of the principles of this science

Chemical

would put an end to many imperfect methods that promote waste. Doubtless we want good officers for the technical contests in which as a nation we are engaged against other countries of the world, but although it is not impossible that we may succeed even with imperfect soldiers, the result will be more glorious if we can lead good men to victory.

DISCUSSION.

The CHAIRMAN said that Mr. Carulla in his paper had touched upon points of very considerable interest. He did not, himself, profess to have any special knowledge of lead, but he did recollect one statement, which he had acquired probably from the text-books, and that was that the presence of a certain proportion of antimony in chamber lead was advantageous in protecting the metal from the action of sulphuric acid. In "Thorpe's Dictionary" reference was made to researches by Calvert and Johnson, and others who had come to the conclusion that lead containing a proportion of impurities was better than lead which was pure and free from these impurities. It seemed strange that it had taken manufacturers so long to find out what lead was best to use for sulphuric acid chambers. We had still much to learn as to the effect of small quantities of foreign elements upon metals generally. Copper occurred to him as an important example. We found engineers specifying that locomotive fire-box plates should be made of pure copper, whereas the opinion was gaining ground that a moderate proportion of arsenic was a great advantage, though he did not know that the subject had ever been scientifically investigated. The Research Committee of the Institution of Mechanical Engineers had an intricate and difficult subject under investigation, the results of which would be of great value. He congratulated the author of the paper upon the application of scientific reasoning in order to find a protection for his leaden pans. He had adopted a very ingenious arrangement. would have thought that the use of high pressure steam under the pan would have been safer, bnt perhaps it would not be so easy to supply steam as, of course, the top of the existing furnace was used in this case and the evaporation was done by waste heat.

One

Professor CLOWES said he would like to ask the writer of the paper a few questions. He wished to know how the iron surface became corrugated permanently. He would like to know also whether these lead evaporation pans were used to any large extent. He had been to a fair number of vitriol works in different parts of the country and he had not seen many of them. They wished Mr. Carulla a wide adoption of his patent. Professor Clowes further stated that he had had occasion to report to an engineering firm why their leaden saturators became violently attacked by heating strong sulphuric acid in them. The specimen of lead cut off the saturator, when heated with the boiling oil of vitriol used, gave off torrents of sulphur dioxide, with formation of lead sulphate. This action could not be repeated with other samples of lead and of strong acid in the laboratory; would Mr. Carulla express an opinion as to whether the difference noticed was due to a difference in the acid or in the lead?

Mr. TAYLOR said he believed that competition and reduced prices had of late years led to inferiority, and he asked the writer of the paper whether he could suggest any ready tests for determining the quality of chemical and other lead upon its delivery from the manufacturer.

Mr. FORTH mentioned an instance of a bleacher's leadlined cistern, used for holding dilute HSO4, wearing out in a very much shorter time than similar ones which had been used in precisely the same way. He wondered whether the bismuth given in Mr. Carulla's analysis of lead could vary enough to be the cause.

Mr. PATON pointed out that lead has such a low limit of elasticity that he thought, even with the suggested arrangement of corrugated iron bed, the buckling of the lead would still occur in the form of little folds on the larger corrugations of the cast-iron plates. He also thought