VOL. LXXVIIT.] PHILOSOPHICAL TRANSACTIONS. * 4^3 



This planet in bulk is 80.49256 times as large as the earth. 



Its density as .220401 to 1. 



Its quantity of matter 17.740612 to 1. 



And heavy bodies fall on its surface 15 feet 3-J- inches in 1 second of time. 



XXIIL Experiments on the Formation of Volatile jllkali^ and on the Affinities 



of the Phlogisticated and light Irflammable Airs. By William Austin, 



M. D, p. 379. 



In the former part of the year J 787 Dr. A. undertook to examine the elastic 

 fluid produced on decomposing volatile alkali by the electric stroke, as first sug- 

 gested by Dr. Priestley. Some alkaline air being thus decomposed, and all its 

 inflammable part separated by combustion in glass vessels inverted in quicksilver, 

 he observed a considerable remainder of phlogisticated air ; and after many accu- 

 rate experiments was fully convinced, that this phlogisticated air had made a part 

 in the constitution of the alkali. This discovery induced him to make a variety 

 of synthetical experiments on the phlogisticated and light inflammable airs, with 

 the hopes of forming volatile alkali from its simple elements. 



First, he endeavoured to combine the phlogisticated and light inflammable 

 airs, by mixing them together in various proportions in their elastic state, and 

 adding to them such substances as he thought likely to promote their uniting 

 and forming an alkali. With this view, he threw up to the mixture of these 

 airs, marine acid air, the marine and vitriolic acids, to which he also joined 

 alkaline air. He tried the effect of cold on these mixtures, by applying to the 

 tubes containing them clothes moistened with ether. He even passed the elec- 

 tric spark repeatedly through them, though with little probability of success. 

 Lastly, he decomposed alkaline air, and tried to re-unite the identical parts 

 which formed it by similar additions; but he could not perceive, that in any 

 instance, volatile aikali was produced from its 2 constituent parts mixed together 

 in their simple aeriform state. 



Yet it is well known, that these 2 bodies unite very readily, when they are 

 not in an elastic state. An unexpected appearance of volatile alkali had been 

 observed by Dr. Priestley and Mr. Kirwan before we were acquainted with its 

 constitution, and by M. Haussman since this discovery of M. Berthollet. An 

 experiment was exhibited before several gentlemen at Sir Joseph Banks's house, 

 some years ago, in which the quantity of volatile alkali produced is very remark- 

 able. In this experiment a few ounces of powdered tin are moistened with some 

 moderately strong nitrous acid, and after they have stood together a minute or 

 two, about 4- an ounce of fixed alkali is mixed with them. A very pungent 

 smell of volatile alkali is immediately perceived. The experiment succeeds 

 equally, if lime be used instead of fixed alkali. Any person, who moistens a 

 drachm or 2 of filings of zinc with a solution of cupreous nitre; and after they 



