286 Analyses of Books. [A p b i l. 



Thus the sulphate of barytes in this mineral exists in the same 

 proportion as the sulphate of strontiau in the crystallized speci- 

 mens. Is this owing to the washing out of the sulphate of 

 etrontian by the action of water, which has probably produced 

 the alteration observable in the state of this bed '. This weathered 

 mineral may, irom the great proportion of barytes which it 

 contains, be" considered as a new variety of sulphate of barytes. 



In the collection of minerals exposed to sale by Mr. Geissler, 

 in Gottingen, amateurs may obtain fine specimens both of the 

 foliated coslestine, of the feathery varieties, and of the weathered 

 kind, as that gentleman was the first person who examined the 

 quarry ; and he supplied himself with abundance of specimens of 

 the strontiau, which was just then making its appearance. 



Article VIII. 

 Analyses of Books. 



Description of the Process of uunnifarliiring Coal Gas for the 

 Li<yhtiiig of Streets, Houses, and Public Bui/di/igs, rvith 

 Etevatioiis, Sec{io)is, and Plans, of the most improved Soi'ts of 

 Apparatus now employed at the Gas Works in London, and the 

 principal provincial Towns of Great Britain ; accompanied 

 with comparative Estimates, exhibiting the most economical 

 Mode of procuring this Species of Light. By Fred. Accum, 

 Operative Chemist, &c. London, 18l9. 



Thls work is intended to supersede a former treatise written 

 by the author upon the same subject, by conveying to the public 

 a'particular detail of the newest improvements introduced into 

 the manufacture of coal gas, and a full account of every thing 

 connected with the subject likely to interest the public. Mr. 

 Accum has had considerable experience in the erection of gas 

 works, and he has availed himself of the experience acquired in 

 the gas works e.-tablished in London and other places. The 

 consequence is, that he has been enabled to communicate a 

 p-reat deal of information in the present work. I cannot do 

 better than recommend it to those who are interested in such 

 subjects. It will fully repay the trouble of a perusal. 



He has divided the work into 16 parts. The first part is 

 employed in pointing out the advantages of this new mode of 

 procuring light. It is, perhaps, not the least interesting chapter 

 of the book ; but as it conveys no new scientific information, I 

 shall pass it over without any particular analysis. 



The second part consisting of only a few pages gives the reader 

 some idea of the mode of pireparing coal gas. This gas is usually 

 considered as carburetted hydrogen gas. I behevQ it always 



