640 PHILOSOPHICAL TRANSACTIONS. [anNO 1755. 



It is also a considerable advantage, that water thus distilled by ventilation, being 

 thus replete and freshened with air, has for present use a more agreeable taste than 

 water distilled without ventilation, which requires the standing a longer time to 

 have its more disagreeable adust taste go off. And as the volatile oil of pepper- 

 mint arises on the wings of the ventilating air during the distillation ; so also may 

 that part of the bitumen, which is volatilized by heat ; as also the volatile urinous 

 salts of the sea-water, which arise from animal substances, be sublimed in the 

 same manner. It was observable, that the water distilled fast, even though the 

 water in the still was belowthe surface of the tin airy box, through which the great- 

 est part of the ascending shower of air rushed. Hence the ventilating air, in as- 

 cending among the vapours, carries them off fast. Hence it is to be suspected, 

 that this method of ventilation will not do well for simple waters, or fermented 

 vinous spirits ; because they being very volatile, much of them may be carried off 

 in waste. It was also observable, that in these distillations of sea-water, no 

 whitish clouds appeared on dropping in solution of corrosive mercury, not even 

 when considerably more than 4 parts in 5 of the water had been distilled over. 

 And it was the same with the mixture of lapis infernalis, lime, and chalk ; whence 

 it is probable, that the lime and chalk seize on and fix the more volatile 

 bittern salt, as does also the lime in the lapis infernalis. And it is well known, 

 that sugar, that sweet salt, cannot be made without lime, on which, as its 

 centre of union, it fixes and granulates. And whereas with a solution of silver 

 in aqua-fortis, which was much weakened and diluted with water, there appeared 

 a faint degree of whitish cloud, in all the above-mentioned distillations, though 

 not with the stronger solution of mercury, till the distillation was carried on 

 much beyond 4 parts in 5 of the water in the still ; when both solutions caused 

 remarkably white clouds, especially the solution of mercury ; which indicates the 

 quantity of the spirit of salt which was raised during the former part of the dis- 

 tillation to be exceedingly small, since it could not seize on, nor disengage the 

 aqua-fortis from the stronger solution of mercury, though it did in a very small 

 degree in the weak solution of silver, so as to let loose a very little of the silver, 

 which thus caused the faint clouds. When a drop of the solution of mercury 

 was dropped into the distilled water, after a drop of the solution of silver, it re- 

 sorbed the silver cloud, and made the water clear, by means of the great propor- 

 tion of acid aqua-fortis that was in it. 



Now in order to make some estimate of the very small quantity of spirit 

 of salt in these several distilled waters. Dr. H. dropped a drop of the solution 

 of silver into an ounce, or 480 grains of pure rain water, which gave no 

 clouds ; but on dropping in a drop of sea-water, which weighed a grain, the 

 white clouds were strong. And since sea-water can dissolve Q times more salt 

 than it has in it ; therefore, supposing the drop to be so fully impregnated with 



