680 PHILOSOPHICAL TRANSACTIONS. [aNNO 17 QO. 



water was employed, the ball of the bottle was plunged into it, and again quickly 

 lifted out, with the necessary shaking interposed, as often as was necessary for 

 communicating the required heat to the liquor; but care was taken to wipe the 

 bottle dry after each immersion, before it was shaken, lest any adhering moisture 

 might by accident get into it. The liquor having by these means been brought to 

 the desired temperature, the next operation was to fill up the bottle exactly to 

 the mark on the neck, which was done with some of the same liquor, by means 

 of a glass funnel with a very small bore. Mr. Gilpin endeavoured to get that 

 portion of the liquor, which was employed for this purpose, pretty nearly to the 

 temperature of the liquor contained in the bottle; but as the whole quantity to 

 be added never exceeded 10 grains, a difference of 10° in the heat of that small 

 quantity, which is more than it ever amounted to, would have occasioned an error 

 of only -gL of a degree in the temperature of the mass. Enough of the liquor 

 was put in, to fill the neck rather above the mark, and the superfluous quantity 

 was then absorbed to great nicety, by bringing into contact with it the fine point 

 of a small roll of blotting paper. As the surface of the liquor in the neck 

 would be always concave, the bottom or centre of this concavity was the part 

 made to coincide with the mark round the glass: and in viewing it care was taken, 

 that the near and opposite sides of the mark should appear exactly in the same 

 line, by which means all parallax was avoided. A silver cap, which fitted tight, 

 was then put upon the neck, to prevent evaporation ; and the whole apparatus 

 was in that state laid in the scale of the balance, to be weighed with all the ex- 

 actness possible. 



The spirit employed by Mr. Gilpin was furnished to him by Dr. Dollfuss, 

 under whose inspection it had been rectified from rum supplied by Government. 

 Its specific gravity, at 6o° of heat, was .82514. It was first weighed pure, in 

 the above-mentioned bottle, at every 5° of heat, from 30 to 100 inclusively. 

 Then mixtures were formed of it and distilled water, in every proportion from 

 TjL. of the water to equal parts of water and spirit ; the quantity of water added 

 being successively augmented, in the proportion of 5 grs. to 100 of the spirit; 

 and these mixtures were also weighed in the bottle, like the pure spirit, at every 

 5° of heat. The numbers hence resulting are delivered in the following table ; 

 where the first column shows the degrees of heat ; the 2d gives the weight of 

 the pure spirit contained in the bottle at those different degrees ; the 3d gives 

 the weight of a mixture in the proportions of 100 parts by weight of that spirit 

 to 5 of water, and so on successively till the water and the spirit are in equal 

 parts. The bottle itself, with its ca^, having been previously counterpoised, 

 these numbers are the weights of the liquor contained in it, ingrains and lOOths 

 of a grain. They are the mean of 3 several experiments at least, as Mr. 

 Gilpin always filled and weighed the bottle over again that number of times, if 

 not oftener. The heat was taken at the even degree, as shown by the thermo- 



