156 Scientific Intelligence. [Aug. 



IV. Process of analyzing Gunpoxvder. 



The process usually employed for analyzing gunpowder consists in 

 washing the powder with water in order to separate the nitre, and 

 treating the residuum with potash, which dissolves the sulphur and 

 leaves the charcoal. Although this process appears to be easy, it is 

 attended with some difficulties, which are discoverable only in the 

 execution of it; the use of this method must not, however, be con- 

 demned ; and is necessary to have recourse to it, if the quantity of 

 charcoal contained in the powder is to be determined in a direct mode. 

 When it is requisite to use this method, it is better to take two por- 

 tions of powder; one of them is to be washed to obtain the nitre ; the 

 residuum is to be dried and weighed. The other portion is to be 

 mixed with an equal quantity of potash and a little water, and the 

 mixture is to be heated : the sulphur readily dissolves, and it is then 

 to be washed until the water has no sulphurous smell, or until it does 

 not precipitate acetate of lead of a black colour. The charcoal is to 

 be dried and weighed. The weight of the sulphur is to be estimated 

 by deducting that of the nitre and charcoal from the weight of the dry 

 gunpowder employed. The results of the analysis may he verified by 

 comparing the weight of the sulphur and charcoal left by the first 

 portion of powder with that given by the second. 



In following this process, there is to me uncertainty in determining 

 the proportion of charcoal, and which exists, also, with respect to the 

 quantity of sulphur. If, therefore, the weight of the sulphur could be 

 determined by direct means, the analysis of the powder would be 

 much more exact. For the purpose of accomplishing this, the follow- 

 ing process is described; and its correctness has been proved by a 

 great number of experiments. 



A certain quantity of powder is to be dried, in order to determine 

 the proportion of moisture which it contains, and to determine with 

 certainty the quantity of charcoal which, in this process, is obtained 

 only by subtraction. The nitre is estimated by washing the powder, 

 evaporating the washings, and fusing the saline residuum. 



In order to determine the quantity of sulphur, 75 grs. of the pow- 

 der, and an equal weight of pure subcarbonate of potash, are to be 

 mixed. The mixture is to be well pulverized in a mortar, and 75 grs. 

 of nitre and 300 of common salt are then to be added. These, after 

 having been thoroughly mixed, are to be heated in a platina vessel in 

 a charcoal fire ; the combustion of the sulphur takes place slowly, and 

 the mass soon becomes white. The operation is then finished : the 

 vessel is to be removed from the fire, and, when cold, the saline mass 

 is to be dissolved in water, the solution is to be saturated with nitric 

 or muriatic acid, and the sulphuric acid precipitated by muriate of 

 barytes. 



There are two modes of effecting this precipitation : the first, which 

 is generally followed, consists in adding a slight excess of muriate of 

 barytes, and collecting the sulphate of barytes produced. This process 

 requires numerous washings, which can only be made at long inter- 

 vals, because sulphate of barytes subsides slowly, especially towards 

 the end of the operation, at which time this salt often remains sus- 

 pended, and goes through the thickcbt filters. If the sulphate of 



