1813.] Manchester Literary and 'Philosophical Society. 57 



12. Description of a Eudiometer, and of other Apparatus 

 emj Joyed in experiments on the Gases. By William Henry, 

 M. D. F. R. S. &c] 1 his eudiometer consists of a glass tube, 

 close at one end, and graduated into 100 parts. The open end 

 of the tube is ground into a very short open glass tube, which is 

 fixed, so as to be air-tight, into a small caoutchouc bottle. The 

 gas to be examined is put into the glass tube, and the bottle is 

 filled with the liquid destined to absorb the oxygen in the gas. 

 The tube is then fixed into the bottle; and by inverting it the 

 gas makes its way into the bottle, whare it may be agitated with 

 violence till the absorption is completed. It may be then mea- 

 sured with facility, and the quantity of absorption ascertained. 



The other instruments described are, 1. A long narrow glass 

 tube, 0*08 in diameter, which is accurately divided into ten 

 equal parts, by drawing mercury by the mouth up to any deter- 

 minate number of these divisions. By this means an equal bulk 

 of mercury is always obtained, and any tube may be graduated 

 with considerable rapidity. I have long employed a similar 

 method of graduating tubes, and can attest its value and accu- 

 racy. I shall hereafter give an account of my method, as it is 

 very easy, and enables us to graduate tubes with great neatness, 

 as well as rapidity. 2. An apparatus for exposing gases to the 

 long continued action of electricity. It consists of a small glass 

 cylinder, terminating in a globular extremity. In this globe two 

 holes are drilled, through which there pass two small glass tubes, 

 which are hermetically sealed into the globe. Through these 

 tubes pass small platinum wires, which are hermetically sealed 

 by the melting of the tube round them. The ends of these 

 tubes are ground away till the extremity of the wires are exposed. 

 These tubes are so placed within the globe that their extremities, 

 are within the striking distance. 



la. A Memoir on the Uric Acid. By William Henry, M.D. 

 F. R. S. &c] Dr. Henry gives a detailed and accurate history 

 of the previous facts ascertained respecting uric acid. He then 

 describes its properties, the salts which it forms, and its decom- 

 position by heat. It may be obtained pure by dissolving urinary 

 calculus, composed chiefly of it, in potash ley, and mixing the 

 solution with an excess of muriatic acid. A white powder falls, 

 which, when washed iii water, and digested in carbonate of 

 ammonia is pure uric acid. This acid possesses the following 

 pr op e rt ies: — 



It has the form of while shining plates. Has no taste nor 

 IDiell. It dissolves in about MOO parts of boiling water. It 

 i-ddrns the infusion of litmus. When dissolved in nitric acid, 

 and evaporated to dryness, it lea* - - a pink sediment. The dry 

 acid is not acted on, nor dis>ohed by, the alkaline carbonates or 



