126 PHILOSOPHICAL TRANSACTIONS. [aNNO 1684-5. 



other places he calls urinosum, nor that spirit of wine was a pure acid, but a 

 spiritus duplicatus. He agrees that no pure acidum is inflammable, but that 

 urinosum and terra must be added. He denies that there is a pure acidum in 

 the world. 



He examines 18 oz. of the gall of an ox, from which he obtains l6 oz. of 

 clear water by distillation, of a stinking oil, and i oz. of a salt earth, in which 

 he says there is a sal acidum : so that he would ascribe inflammability to belong 

 rather to the acidum than oleosum. 



M. Kunkel proceeds to give an account of Dr. Voight's opposite sentence ; 

 who instances in his common distillation of wine, viz. that after the spirit of 

 wine per balneum mariae is separated from the wine, that which remains in the 

 vessel becomes sour, and will not burn, though perhaps somewhat of a sub- 

 jugated oil may be mixed with it: but if there be separated any oil from the 

 acid, it then burns per se. 



M. Kunkel endeavours to prove sp. vini to be no oil ; because oil will not 

 intoxicate a man ; and because acids, though of different families, do all unite 

 and mix, and so also do oils. 



M. Kunkel's opponent (Dr. Voight) proceeds to the regnum minerale, and 

 absolutely denies a heat, flame, or light, to be properly inherent in any acid, 

 but that some central oils, not easily separated from mineral acids, produce 

 those incalescent efl-ects. Rain water, he says, affords oil and volatile salt, but 

 no inflammable acid. He says all acids, though ever so pure, if evaporated or 

 distilled off, will always leave in the bottom of the retort, or other vessel, a 

 materia pinguis et unctuosa, out of which an inflammable oil may be brought. 

 He concludes saying, that it suffices to prove, that acidity does in nowise dis- 

 pose a body to inflammability, because olea expressa et distillata burn and 

 flame more readily, when they are purged of all mixture of acidity : as oleum 

 lini, terebinthinae, anisi, fceniculi, when distilled per cineres, and other alcalia 

 that detain the acida. 



M. Kunkel, in his answer, denies that in these mineral acids, particularly oil 

 of vitriol, any oil is contained. Since Dr. Voight declares all heat to depend 

 on bodies, on the score of their being oily, he (Mr. K.) demands that he will 

 shew him an experiment, how to produce heat with the mixture of any oil and 

 water ; as M. Kunkel has often done with acids and water. 



The adversary. Dr. Voight, proceeds to lay down several positions. 1 . That 

 oil of vitriol is the most fixed acid, and gives more heat than spirit of wine 

 vi'hile flaming. 2. That fixed bodies are only respectively so. 3. That acids, 

 by repeated distillations, may be brought to such a degree of subtlety (I suppose 

 he means volatility,) as spirit of wine. 4. Any surmise about an acidum occul- 



