COMPOSITION AND ANALYSIS OF GUNPOWDER. 181 



possible to preserve powder free from moisture, and from the loss 

 of a part of its sulphur in hot climates, by keeping it in glazed 

 earthen bottles, or in bottles made of copper or tin, well corked ? 



This disposition to attract the humidity of the air, is different 

 in different sorts of powder, it is the least in that which is made 

 from the purest saltpetre ; ptire saltpetre, which has been dried as 

 gunpowder is dried, does not become heavier by exposure to the 

 atmosphere ; at least, its increase of weight is very small, not amount, 

 jng, as far as my experiments have informed me, to above one 72d 

 part of its weight ; I rather think that it does not acquire any in. 

 crease of weight. But saltpetre mixed with sea salt, attracts the 

 humidity very sensibly ; and hence, though there should be the same 

 weight of saline matter in a certain weight of gunpowder, yet the 

 goodness of the powder may be very variable, not only from the 

 foreign saline matter, be it sea salt, or any other salt, injuring the 

 quality of the powder as being an improper ingredient, but from its 

 rendering the powder more liable to become humid. 



Saltpetre being the ingredient, in which there is the greatest room 

 for fraud, in the composition of gunpowder, and on the quantity of 

 which its strength chiefly depends, the reader will excuse the mi. 

 nuteness of the following process, to ascertain the quantity of salt, 

 petre contained in any specimen of gunpowder. 



Take any quantity of gunpowder, pound it in a glass mortar till 

 all the grains are broken, lay it before a gentle fire till it be quite 

 dry ; in that state weigh accurately any quantity of it, suppose four 

 ounces; boil these four ounces in about a quart of water; the 

 boiling need neither be violent nor long continued, for the water 

 will readily dissolve all the saltpetre, or other saline matter, and 

 not a particle of either the sulphur or the charcoal of the powder. 

 In order to separate the water containing the saltpetre, from the 

 sulphur and charcoal, pour the whole into a filter made of brown 

 paper; the water containing the saltpetre will run through the 

 paper, and must be carefully preserved ; the charcoal and sulphur 

 will remain upon the paper. But as some particles of saltpetre 

 will stick both to the filtering paper, and to the mass of sulphur and 

 charcoal, these are to be repeatedly washed, by pouring hot water 

 upen them, till the water in running through the filter is quite in. 

 sipid; then we may be certain, that we have all the saltpetre ori- 

 ginally contained in the powder, now dissolved in the water, and 



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