Dr. Hare on Fused Garhon. 283 



moderate proportion, and where great accuracy is desirable. 

 Whenever (it may again be remarked) olefiant gas is present 

 in a mixture, it should always be removed by chlorine before 

 proceeding to expose the mixture to the agency of the spongy 

 metal. 



It can scarcely be necessary to enter into further details re- 

 specting methods of analysis, the application of which to par- 

 ticular cases must be sufficiently obvious from the experiments 

 which have been described on artificial mixtures. The ap- 

 paratus required is extremely simple, consisting, when the balls 

 are employed, of graduated tubes of a diameter between 0*3 and 

 0'6 of an inch, or, when an increased temperature is used, of 

 tubes bent into the shape of retorts, of a diameter varying with 

 the quantity of gas to be submitted to experiment, which may 

 be from half a cubic inch to a cubic inch or more. These when 

 in use may be immersed in a small iron cistern containing 

 mercury, and provided with a cover in which are two holes, 

 one for the tube and the other for the stem of a thermometer, 

 the degrees of which are best engraved on the glass. 



By means of these improved modes of analysis, I have al- 

 ready obtained some interesting illustrations of the nature of 

 the gases from coal and from oil. I reserve, however, the 

 communication of them till I have had an opportunity of pur- 

 suing the inquiry to a greater extent, and especially of satis- 

 fying myself respecting the exact nature of the compound of 

 charcoal and hydrogen, discovered some years ago by Mr.Dal- 

 ton, in oil gas and coal gas, which agrees with olefiant gas in 

 being condensible by chlorine, but differs from it in affording 

 more carbonic acid and consuming more oxygen. 



XLV. Remarks respecting Mr. Vanuxem's Memoir on a Fused 

 Product, erroneously Identijcd mth the Fused Carbon of 

 Professor Sii-li-Man ; vcith some additional Facts and Obser- 

 vations* By Dr. Robert Hare. 



To Alexander Tilloch and R. Taylor, Esqs. Editors of the 

 Philosophical Magazine and Journal. 

 Gentlemen, 



OBSERVING that a memoir by Professor Vanuxem, found- 

 ed on an unlucky mistake, has been re-published in your 

 Magazine (vol. Ixiv. p'. 4G7), 1 beg tiiat injustice to Prof. Silli- 

 niau you will, at as early a period as possible, allow the remarks 



• Published in llic PhiiaUd|)hia Medical Journal, and Siliiman's Journal 



in the biiinnicr of lb!24. . 



N n 2 which 



