TABLE XVI. Coed-Talon, Hot Blast. Weight in lbs. Results reduced to those of bars 1.00 in. square, and 2 ft. 3 in. between supports. Product Modulus of Breaking Ultimate bxd, or weight deflection power of Temp. (b). (d). resisting impact. of temperature. ble to a considerable extent in the experiments ranging from 26° up to 190° weaker, and less secure under the effects of heavy strain. This is observaand probably less rigid in its nature; and I apprehend it will be found The infusion of heat into a metallic substance may render it more ductile, per cent. in the hot blast. for the hot blast, or 15 per cent. loss of strength in the cold blast, and 10 being a diminution in strength as 100: 85 for the cold blast, and 100: 90 The hot blast at 21° and 190°, is in strength as 811: 731; The cold blast at 26° and 190°, is in strength as 874: 743, TABLE XVII. Coed-Talon Cold Blast. To determine the relative strengths of Coed-Talon hot and cold blast iron to resist the transverse strain under different degrees of temperature. No. 2 Iron. Experiment 6. No. 3 Iron. No. 3 Iron. No. 2 Iron. Experiment 9. Experiment 11. No. 2 Iron. Depth of bar, 1.030 Depth bar, .995 Depth bar, 1.015 Depth bar, 1.004 Depth bar, 1.026 Distance between Distance between Distance between Distance between Weight in Tem lbs. Weight in supports, 2ft 3in. supports, 2ft 3in Distance between Weight in lbs. lbs. Weight in lbs. 900 broke 212° 956 broke 600° 672 broke it, 784 broke. This Broke in boiling Broke in melted after the weight bar was a deep had been on half orange colour in water. No. 3 Iron. Experiment 8. lead. a minute. The the dark. There deflection was was no time to Depth bar, .995 Depth bar, .987 considerable. The measure the de Breadth 1.000 Breadth .997 Distance between Distance between Tem light. Weight in Weight in. lbs. lbs. 934 broke 2120 1124 broke 600° Broke in hot water. Broke in boiling Broke in melted water. lead. Coed-Talon No. 3 cold blast iron exhibits greater density in the arrangement TABLE XVIII. Coed-Talon Hot Blast. Results reduced to those of bars 1.00 inch square, and 2 feet 3 inches between impact. 800 broke 212° 889 broke 600° Broke in boiling water. .986 Broke in melted lead. No. 2 Iron. Temp. Weight in lbs. 811 broke 600° 896 broke. Ultimate deflec Ultimate deflec tion=.386. Broke tion=. Ultimate deflec- Broke in melted =.346. Broke tion=.356. Broke lead. Bar perceptibly in hot water. in hot water. in hot water. This iron presents an appearance of greater ductility and softness than the No. 3, cold blast. From the blue tinge which the fracture exhibits, it is evidently an iron possessing the powers of being worked to a greater degree than the cold blast. Results reduced to those of bars 1.00 inch square, and 2 feet 3 inches between In pursuing the experiments, it unfortunately occurred that the stock of No. 2 Coed-Talon metal became exhausted, a circumstance which interrupts the comparisons from below the freezing point to that of melted lead. The No. 3 should have been broken at all the points of temperature, in order to have ascertained the loss of strength sustained upon this iron by the increase of heat. This was, however, not accomplished, and we can now only compare the two qualities, No. 2 and No. 3, at the boiling point of water, and then proceed to the temperature of melted lead. I have already noticed that a considerable failure of the strength took place after heating the No. 2 iron from 26° to 190°. At 212° we have, in the No. 3, a much greater weight sustained than what is indicated by the No. 2 at 190°; and at 600° there appears in both hot and cold blast the anomaly of increased strength as the temperature is advanced from boiling water to melted lead, arising from the greater strength of the No. 3 iron. A number of the experiments made on No. 3 iron of different sorts have given extraordinary and not unfrequently unexpected results. Generally speaking it is an iron of an irregular character, and presents less uniformity in its texture than either the first or second qualities; in other respects it is more retentive, and is often used for giving strength and tenacity to the finer metals. Recurring to the No. 2 iron, it will be observed that the strength continued to diminish as the temperature was increased. Heating the cold blast iron in Experiments 11 and 12 to a perceptibly red colour, we have the breaking weights 663 and 723; whereas, in the hot blast, at nearly the same temperature, the breaking weight is 829.7, being as 693 (the mean) to 829, or in the ratio of 1000: 1289. From the experiments in Table 1, it appears that a bar of cold blast iron 1 inch square and 2 feet 3 inches between the supports, broke at the ordinary temperature of the atmosphere with 836.9, and in No. 3 cold blast from Table III, the breaking weight is 1137.3. This gives an excess of strength for the No. 3 iron of at least one-fourth. When the bars were heated to a blood red the utmost care was taken to break them without loss of time. In every instance the deflection was considerable; rather more than 1 inches was observed on the 2 feet 3 inches bars before they gave way. Comparative strength and power to resist impact of the Coed-Talon hot and cold blast irons, at various temperatures. Modulus of elasticity in lbs, for a base of 1 inch square. Temperature. Coed-Talon Cold Blast. Coed-Talon Hot Biast. The above summary of results on the strength of the hot and cold blast irons is, with one exception, in favour of the cold blast. On the other hand, the power to resist impact appears, with one exception, also, on the side of the hot blast. Having prosecuted these inquiries through a considerable range both of time and temperature, and having united my efforts to those of Mr. Hodgkinson on the transverse strain, I shall, before closing this report, give a general summary, with the results of which he has kindly favoured me, from all the irons exprimented upon in this way. Those results will exhibit in one column the relative and proportionate strength of each iron, and in the other the ratio of the forces to resist impact. Before closing the experiments, it may, however, be proper to state, in addition to the methods described in the preceding inquiry, that of grinding was adopted. For this purpose, an apparatus was made to grind each iron under an equal pressure, in order to ascertain the comparative resistances of different specimens of the same size, as compared with the results from chipping and filing given before. This was done with equal weights, upon VOL. XXV.-No. 1.-JANUARY, 1840. 6 |