598 Intelligence and Miscellaneous Articles. 



structures, or to the "exudation-corpuscles" of authors : and, as 

 he shows, the floating red blood-discs have their origin in parent 

 cells. 



COMPOSITION OF MELLIT1C ACID. 



M. F. Wcehler obtains this acid by decomposing the mellitate of 

 lead or of silver ; the first by hydrosulphuric and the last by hy- 

 drochloric acid, any excess of the latter being separated by evapo- 

 ration. Mellitic acid is very soluble, and crystallizes from a concen- 

 trated solution in small reticulated crystalline needles of a silky 

 lustre. This acid suffers no change by exposure to the air; it has 

 a strongly acid taste, fuses when heated, and burns in the air with 

 a brilliant sooty flame, with an aromatic smell, and yielding a great 

 quantity of carbon, without leaving any residue. When heated in a 

 retort a portion is volatilized without decomposition, but the larger 

 proportion is completely decomposed. Crystallized mellitic acid 

 does not yield water till heated to nearly 400° Fahr. 

 It is composed of nearly — 



Carbon .... 42*38 or 4 equivalents. 



Oxygen 41-21 . . 3 .... 



Water .... 16-41 ..1 



100- 



L'Institut, No. 383. 



SALTS OF LEAD CONTAINING ACIDS OF OXYGEN AND AZOTE. 

 M. Peligot has re-examined the salts of lead which contain the 

 acids formed by oxygen and azote. He observes that Proust, about 

 thirty years since, first obtained the yellow salt of lead by dissolving 

 metallic lead in solution of the nitrate. He was of opinion that the 

 salt contained a suboxide of lead. It was however shown by Ber- 

 zelius, that the lead was dissolved, not by reducing the oxide of lead 

 to a lower state of oxidizement, but at the expense of the nitric acid. 

 The subnitrite which contains the least of oxide of lead, was found 

 both by Berzelius and Chevreul to consist of 



Acid and water 20 



Oxide 80 



100 



The subnitrite containing most lead was found to consist of 



Berzelius. Chevreul. 



Acid 10175 9-9 



Oxide 89-82 5 90-1 



100- 100- 



M. Chevreul showed, however, that notwithstanding this agreement 

 in the analyses, the nitrites which he had prepared were different 

 from those of Berzelius. Thus the latter found no water in the ni- 

 trite containing most oxide, while Chevreul did. Berzelius says, 

 that this salt crystallizes in small scales of a brick-red colour ; while 

 that obtained by Chevreul was in scales of a flesh-colour, &c. 



In experimenting on these compounds, M. Peligot generally agreed 



