VOL. LXXI.] PHILOSOPHICAL TRANSACTIONS. 113 



was constantly and very sensibly diminished. He afterwards made use of aetherial 

 oil of turpentine ; and then of small quantities of quicksilver ; but still with no 

 better success. Every thing he mixed with the powder, instead of increasing, 

 served to lessen the force of the charge. Common pulvis fulminans is made of 

 1 part of sulphur, 1 parts of salt of tartar, and 3 parts of nitre ; and if we may 

 judge by the report of the explosion, the elastic force of this compound is con- 

 siderably greater than that of gunpowder. Mr. T. tried the. effect of mixing 

 salt of tartar with gunpowder ; having provided some of this alkaline salt in its 

 purest state, thoroughly dry, and in a fine powder, he mixed n O grains of it 

 with 145 grains of gunpowder; and on discharging a bullet with the mixture, 

 he found that the alkaline salt had considerably lessened the force of the powder. 

 Mr. T. next made use of sal ammoniacum. That salt has been found to pro- 

 duce a very large quantity of elastic air, or vapour, when exposed to heat under 

 certain circumstances ; but when 20 grains of it were mixed with a charge of 

 gunpowder, instead of adding to its force, it diminished it very sensibly. 



Most, if not all, the metals, are thought to produce large quantities of air 

 when they are dissolved in proper menstrua, and particularly brass, when it is 

 dissolved in spirit of nitre. Desirous of seeing if this could be done by the 

 flame, or acid vapour of fired powder, Mr. T. mixed 20 grains of brass in a 

 very fine powder, commonly called brass dust, with 145 grains of powder, and 

 with this compound and a fit bullet he loaded the barrel and discharged it ; but 

 the experiment showed, that the force of the powder was not increased by the 

 addition of the brass dust, but the contrary. It seems probable however, that 

 neither brass dust nor sethiops mineral are of themselves capable of diminishing 

 the force of gunpowder in any considerable degree, otherwise than by filling up 

 the interstices between the grains, and obstructing the passage of the flame, and 

 so impeding the progress of the inflammation. And hence it appears, how 

 earthy particles and impurities of all kinds are so very detrimental to gunpowder. 

 It is not that they destroy or alter the properties of any of the bodies of which 

 the powder is composed, but simply, that by obstructing the progress of the in- 

 flammation, they lessen its force, and render it of little or no value. Too much 

 care therefore cannot be taken, in manufacturing powder, to free the materials 

 from all heterogeneous matter. 



Of an attempt to shoot flame instead of bullets. — Having often observed paper 

 and other light bodies to come out of great guns and small arms inflamed, Mr. 

 T. was led to try if other inflammable bodies might not be set on fire in like 

 manner, and particularly inflammable fluids ; and he thought if this could be 

 effected, it might be possible to project such ignited bodies by the force of the 

 explosion, and by that means communicate the fire to other bodies at some con- 

 siderable distance -. but in this attempt he failed totally. Mr. T. never could set 



VOL. XV. Q 



