TOL. LVI.] PHILOSOPHICAL TRANSACTIONS. 299 



and that which I haveoftenest made use of, is that represented fig. 14; where a 

 is the bottle, into which the air is to be transferred; it is supposed to be filled with 

 water and inverted into the vessel of water defg, and suspended there by a 

 string; the line dg is the surface of the water: b represents a tin funnel held 

 under the mouth of the bottle: c represents the inverted bottle, out of which 

 the air is to be transferred; the mouth of which is lifted up till the air runs out 

 of it into the funnel, and thence into the bottle a. 



In order to transfer air out of a bottle into a bladder, the contrivance fig. 1 5 

 is made use of. a is the bottle out of which the air is to be transferred, inverted 

 into the vessel of water fghk: b is a bladder, whose neck is tied fast over the 

 hollow piece of wood cc, so as to be air-tight. Into the piece of wood is run a 

 bent pewter pipe d, and secured with lute.* The air is then pressed out of the 

 bladder as well as possible, and a bit of wax e stuck on the other end of the pipe, 

 so as to stop up the orifice. The pipe, with the wax on it, is then run up into 

 the inverted bottle, and the wax torn off by rubbing it against the sides. By 

 this means, the end of the pipe is introduced within the bottle, without suffering 

 any water to get within it. Then, by letting the bottle descend, so as to be to- 

 tally immersed in the water, the air is forced into the bladder. 



The weights used in the following experiments, are Troy weights, 1 ounce con- 

 taining 480 grains. By an ounce or grain measure, I mean such a measure as 

 contains one ounce or grain Troy of water. 



Part i. — Containing Experiments on Inflammable Air. 



I know of only three metallic substances, namely, zinc, iron, and tin, that 

 generate inflammable air by solution in acids: and those only by solution in the 

 diluted vitriolic acid, or spirit of salt. Zinc dissolves with great rapidity in both 

 these acids; and, unless they are very much diluted, generates a considerable 

 heat. One ounce of zinc produces about 356 ounce measures of air, the quan- 

 tity seems just the same whichever of these acids it is dissolved in. Iron dis- 

 solves readily in the diluted vitriolic acid, but not near so readily as zinc. One 

 ounce of iron wire produces about 412 ounce measures of air: the quantity was 

 just the same, whether the oil of vitriol was diluted with \\y or 7 times its 

 weight of water: so that the quantity of air produced seems not at all to depend 

 on the strength of the acid. Iron dissolves but slowly in spirit of salt while cold: 

 with the assistance of heat it dissolves moderately fast. The air thus produced 

 is inflammable; but I have not tried how much it produces. 



• The lute used for this purpose, as well as in all the following experiments, is composed of al- 

 mond powder, made into a paste with glue, and beat a good deal with a heavy hammer. This is 

 the strongest and most convenient lute I know of. A tube may be cemented with it to the moutli 

 of a bottle, so as not to suffer any air to escape at the joint; though the air within is compressed by 

 the weight of several inches of water. — Orig. 



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