418 Capt. Noble and Mr. F. A. Abel [June 18, 



experimental observations. When, however, the heat stored up in the 

 solid residue is taken into account, it is found that calculation and 

 experimental observation accord with great exactness ; and the authors 

 express the relation between the tension of the products in the bore of a 

 gun and the volume they occupy by the equation 



< 30 > 



The temperature of the products of explosion during their expansion 

 in the bore of a gun is then given, and the maximum work that can be 

 realized from powder for any given expansion, as also the total theoretic 

 work of powder, are given. 



The principal results of the authors' investigations are summarized as 

 follows, and for convenience are computed upon one gramme of powder, 

 occupying 1 cub. cent. : 

 0. (a) First, with regard to powder fired in a, close vessel. 



1. On explosion, the products of combustion consist of about 57 hun- 

 dredths, by weight, of matter, which ultimately assumes the solid form, and 

 43 hundredths, by weight, of permanent gases. 



2. At the moment of explosion, the fluid products of combustion, doubt- 

 less in a very finely divided state, occupy a volume of about *6 cub. cent. 

 " 3. At the same instant, the permanent gases occupy a volume of 

 4 cub. cent., so that both the fluid and gaseous matter are of approxi- 

 mately the same specific gravity. 



4. The permanent gases generated by the explosion of a gramme of 

 powder are such that, at C. and 760 mm. barometric pressure, they 

 occupy about 280 cub. cents., and therefore about 280 times the volume 

 of the original powder. 



5. The constituents of the solid products are as shown in Tables II. & III. 



6. The composition of the permanent gases is shown in the same Tables. 



7. The tension of the products of combustion, when the powder fills 

 entirely the space in which it is fired, is about 6400 atmospheres, or 

 about 42 tons per square inch. 



8. The tension varies with the mean density of the products of com- 

 bustion, according to the law given in equation (3). 



9. About 705 gramme-units of heat are developed by the decompo- 

 sition of one gramme of powder, such as used in the experiments. 



10. The temperature of explosion is about 2200 C. 

 (b) When powder is fired in the bore of a gun. 



1. The products of explosion, at all events as far as regards the pro- 



* In this equationjp denotes the tension and v the volume of the products of explo- 

 sion, a the proportion occupied by the solid products, C v and C p the specific heats of the 

 permanent gases at constant volume and pressure, X the mean specific heat of the non- 

 gaseous products, /3 the ratio between the weights of the gaseous and non -gaseous 

 portions of the charge. 



