40 Notices respecting New Books, 



ject to ascertain the quantities of carbonic acid gas and water 

 yielded by a substance, it is, of course, necessary to operate 

 on a known weight ; but this being once determined, there is 

 no fear, as in the common methods, of exposing the substance 

 to the atmosphere as long as may be necessary. The hy- 

 grometric properties of the oxide of copper, as well as its 

 property of condensing air, are also completely neutralized ; 

 for the whole, at the end of the experiment, being left pre- 

 cisely in the same state as it was at the commencement, the 

 same condensation of course must take place, and any little 

 differences that may exist are rendered quite unimportant 

 from the bulk of oxygen gas operated on, which of course 

 should, in all instances, be considerably greater than that of 

 the carbonic acid gas formed. Another advantage of this 

 method is, that more perfect combustion is insured by it than 

 by any other that I am acquainted with. There is also no 

 trouble of collecting or estimating the quantity of water, — a 

 part of the common process attended with much trouble, and 

 liable to innumerable accidental errors besides those already 

 mentioned, and which there is no method of obviating or ap- 

 preciating : here, on the contrary, the results are obtained in 

 an obvious and permanent form, and, from the ease with 

 which they are thus verified, comparatively very little subject 

 to error. 



It need scarcely be stated, that the form and principles of 

 this apparatus render it well adapted for many other chemical 

 operations besides the analysis of organized substances. Such, 

 for example, as the reduction of oxides by hydrogen, and a 

 variety of others that will readily occur to the practical 

 chemist. 



[To be continued.] 



X. Notices respecting New Books. 



Account of a New Work, entitled, A Treatise on the Steam-Engine; 

 Historical, Practical, and Descriptive. By John Farey, Engineer. 

 London. Published by Longman, Rees, and Co. in 4to. Price Five 

 Guineas. 



CONSIDERING the great extension which has been given to all 

 branches of our national manufactures, by the application of 

 steam power to expedite laborious operations, it is surprising that 

 no competent engineer has hitherto undertaken to publish on this 



taken that the gases are saturated with moisture: the errors from this cause 

 are thus rendered definite, and are easily corrected by tables calculated for 

 the purpose from the most accurate data, and which will be given in a sub- 

 sequent communication. 



subject, 



