518 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



of windage seems to increase with the charge. It is tlms rendered experi- 

 mentally evident that it is a great error to make the correction for loss of 

 velocity by windage a constant for all charges in the same gun. That this 

 is an error was indeed a priori probable. It is somewhat remarkable that 

 it should have been so long permitted to stand unquestioned. 



Mr, G. Bartlett. — In the article just read, Prof. Barnard goes through his 

 summary of the experiments made to ascertain the force of gunpowder, all 

 of which he condemns, and then says that there has been a set of experi- 

 ments made by Buusen which are so satisfactory as to leave nothing to 

 desire. Now we have had a full account of these experiments last winter 

 at one of our meetings by Prof Joy who v/as then our chairman. He said 

 that the experiments of Bunsen were made in the open air. Now I want to 

 raise the point, how important the diiference is between burning gunpowder 

 under and not under pressure. Bunsen gave a long list of the products of 

 burnt gunpowder, among which was the nitrate of ammonia, this in itself 

 would utterly destroy Bunsen's experiments. We know the volume of the 

 gases, supposing the temperature to be the same, would fill a larger space 

 than he gives, and we know the chemical changes to be different by burn- 

 ing powder under an intense heat. So I take it, these experiments are 

 entirely vitiated on this point. What is necessary to take into account is 

 the capacity of these several substances for heat. Gases expand according 

 to a certain law, and according to an increase of temperature, but these 

 substances take different quantities of heat, that is their capacity for heat 

 varies with the temperature, and for these immensely high temperatures 

 their capacity has never been ascertained. Prof. Barnard goes through 

 two experiments to find out the force of gunpowder under chemical and 

 mechanical action. The chemical is at fault, but the mechanical is easier 

 to find out, and the result appears to be 150,000 pounds on the square inch« 



Mr, Norman Wiard. — At the time experiments were made at the Spring- 

 field armory, they found that musket barrels had only a pressure of 5,000 

 pounds on the square inch, and that a gunbarrel was not permanently 

 enlarged 'by powder, but is by water. In the efforts to launch the " Great 

 Eastern," in England, they used hydraulic presses in which there was a 

 pressure of 5,000 pounds on the square inch, although these presses burst, 

 yet guns made at the same foundry in which these presses were built stood 

 the force of gunpowder, but were burst with water. 



The Chairman. — The method of making gunpowder is very old, and in 

 early times it was made without any knowledge of chemistry, for all the 

 substances of which it is composed are found in nature; one of these sub- 

 stances, nitre, exists in many places in this country, andwas very abundant 

 in the great cave in Kentucky. It is quite remarkable that the propor- 

 tions for making gunpowder, which are now deemed the best, are the 

 same as the earliest known receipts. These are 75 parts saltpetre, 125 

 sulphur, I2'5 charcoal. Although the American, French and Eiiglish 

 powders are not precisely alike, that is probably most effective which, on 

 explosion, unites in true chemical proportions. 



Mr. Stuart. — The nitrate of potash is found in Japan, in greater abun- 

 dance than in any other part of the world. 



Mr, Wiard then read a paper on the bursting of guns. 



