Intelligence and Miscellaneous Articles. 24-S 



ON THE BIBASIC ARSENIATE OF AMMONIA AND MAGNESIA. 

 BY M. LEVOL. 



The author observes, that, notwithstanding the striking analogies 

 presented by arsenical and phosphoric compounds, it does not ap- 

 pear to have been ascertained whether an arsenical compound exists, 

 corresponding to the most important of the ammoniaco-magnesian 

 double phosphates, or that which occurs among certain products of 

 animal organization, and which is so frequently employed in chemi- 

 cal analyses, on account of its insolubility, to determine the quantity 

 of phosphoric acid. 



The author thought it would be interesting to determine if it were 

 possible to produce an arseniate analogous to this phosphate, and to 

 apply it, on account of its insolubility, to ascertain the quantity of 

 arsenic acid ; and he found, in fact, that such a salt exists, and that 

 it resembles in every respect the bibasic phosphate of the same bases, 

 and its formula is similar to that which Berzelius assigns to the 

 phosphate 2NH 3 , 2MgO, AsO + lOHO. 



This salt is obtained like the corresponding phosphate, that is to 

 say by pouring a soluble double ammoniaco-magnesian salt into a 

 solution of arsenic acid, after having rendered it ammoniacal ; like 

 the phosphate, it does not immediately appear, but only after the 

 lapse of a few seconds, unless it be agitated ; it deposits in the same 

 way in the form of very small crystals on the sides of the vessel ; its 

 insolubility may also be compared to that of the phosphate : one part 

 of arsenic acid, diluted with 56818 parts of ammoniated water, was 

 rendered sensible soon after the addition of a few drops of a concen- 

 trated solution of ammoniaco-magnesian sulphate ; and the author is 

 of opinion that it would be difficult to mention two salts more ex- 

 actly comparable each to the other, than the phosphate and arseniate 

 under consideration. 



The new salt was applied in a very difficult case of chemical ana- 

 lysis, that of the quantitative separation of arsenious and arsenic 

 acids, the former not yielding a double insoluble salt with ammonia 

 and magnesia. When the precipitate is collected, it is to be dried 

 and calcined to redness, taking care that it is not exposed to any re- 

 ducing influence ; there remains 2MgO, As0 5 = 5574 of 100 of the 

 new salt, which represent 41 '02 of arsenic acid. The author sug- 

 gests that the ammoniaco-magnesian double salts might be employed 

 as remedies in cases of poisoning by arsenic acid. — Ann. de Ch. et 

 de Phys., Aout 1846. 



examination of a fossil resin found near eu (seine- 

 inferieure). by mm. lassaigne and chevallier. 



This substance may be mistaken for amber, which it resembles in 

 its yellowish colour, transparency, fusibility and combustibility. 

 One specimen of a pale yellow colour, was of sp. gr. 1*094; the 

 other, which was reddish-yellow, had a sp. gr. of 1. 



The first of these specimens was reduced to fine powder, and ma- 



