164- Intelligence and Mi^ellarieous Articles. 



magnifying power in such combinations as when the difference be- 

 tween the lenses is, Ipss." 



The 18th and 19th chapters, which are written by Dr. Goring, 

 ^reat of the verification qf microscopic phsenomena, and of the exact 

 paethpd of appreciating the quality of microscopes and engiscopes. 



These two chapters are of great practical value, and will be read 

 with much interest both by the naturalist and the optici?^n. 



The last chapter of the volume is entitled Miscellnneous Fragi^ents, 

 9nd contains many useful directions and methods, especially ia re^r- 

 ence to the preparation and mounting of microscopic objects. 



Such is a brief analysis of the work before us. We earnestly re- 

 commend it both to the general and the scientific reader as an originsj, 

 a valuable, and an ingenious work; and we trust it will meet with 

 such success as to disappoint the expectations of the author, who, in 

 the following passage of his preface, has given a just though melan- 

 choly picture of the present state of our scientific literature. 



" In the present forlorn state of spientific literature, it is rare that 

 the author gets * a return of his outlay,' and, indeed, very often loses 

 one half, the demand for illustrated scientific books being less than 

 for that of any other class : it is therefore in vain for an author to 

 expect pecuniary remuneration for his tim« and labour. All that is 

 desired for this work is, that it may receive sufficient patronage to re- 

 turn its expenses." 



'f^r 



XXXV. Intelligence and Miscellaneous Avliclea^ 



ON TH 



E CAUSE OF THE PRODUCTION OK HEAT BY FBICTION 

 AND PERCUSSION. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



YOU would much oblige me by explaining, in your valuably 

 Journal, the "cause of heat frono friction." 

 Iron laid upon an anvil and receiving violent blows from 3 ham- 

 mer, will become red hot, partly from the diminished volumje of 

 the iron, and still more, as it is supposed, from an electrical causfiw 

 May it not arise, and chiefly, from the disengaged caloric latenit 

 in the particles of air which viust intervene between the hamraer 

 or anvil, and the iron ? 



I am not aware of any experiments having been tried in vacuo. 

 Should you think this worthy of ipgertion in your JourpaJ, 

 you will oblige me. And I believe thi^ idfia has not occurred^ before 

 to any one. 



I am. Gentlemen, your obedient Servant;, 



E. 



PREPARATION OK CHLQRA.TE OF POTASH. 



M. Liebi" proposes the followinir process for obtaininc: chlorate pf 



poUU'h. ' Vi.KM.t.oS-v'). 



