236 Intelligence and Miscellaneous Articles. 



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pressure separated into very fine needles ; when quickly heated to 

 212° to 248° Fahr., it loses part of its water; at 392° Fahr. it re- 

 tains two equivalents of water, and these cannot be expelled at a 

 temperature lower than 482° to 500° Fahr. 



When heated slowly and progressively, this salt effloresces with- 

 out fusing in its water of crystallization ; it may in this mode be 

 deprived of the whole of its water of crystallization without being 

 fused ; it merely agglutinates slightly. 



The formula of this salt derived from analysis is ZnO, SO 3 , MgO, 

 SO 3 -f- 14HO, which indicates 471 7 per cent, water; the loss of 

 water by experiment was 47' 12; the salt heated to 392° Fahr. re- 

 tained ten equivalents of water. 



From the preceding and the analyses of various other salts which 

 the author prepared, he arrives at the following among other con- 

 clusions : — 



1. Sulphate of zinc containing seven equivalents of water, re- 

 tains the whole of it in the compound which it forms with the alka- 

 line or alkalino-earthy sulphates. 



2. The sulphates of zinc and magnesia combine equivalent to 

 equivalent, and the resulting compound contains a quantity of water 

 equal to the sum of the quantities which both salts contained when 

 separate, that is to say, fourteen equivalents, if the double salt cry- 

 stallizes at common temperatures. 



3. The simple sulphates of zinc, copper and nickel yield all their 

 water at a little above 212° in a long-continued current of air, in- 

 stead of retaining one equivalent, as stated by Prof. Graham, at 400° 

 Fahr. 



4. The simple sulphates of zinc, magnesia, copper and nickel 

 combine with other sulphates, or with each other without elimina- 

 tion of the water. — Ann. de Ch. et de Phys., Fevrier 1846. 



PREPARATION OF HYPOPHOSPHITES. 



M. A. Wurtz prepared almost the whole of these salts, which he 

 analysed, by the double decomposition of soluble sulphates with hypo- 

 phosphite of barytes ; the most ceconomical method of preparing the 

 last-mentioned salt, is to boil a solution of sulphuret of barium with 

 phosphorus, until gas ceases to be evolved. If the ebullition has 

 been long continued, the sulphuret of barium is almost entirely 

 decomposed, and a slight excess only is left, which may be se- 

 parated by carbonate of lead. Sometimes, however, the excess of 

 sulphuret is more considerable ; it is then proper to separate it by 

 cautiously adding small quantities of sulphuric acid to the hot filtered 

 liquor, as long as sulphuretted hydrogen is disengaged. If the liquor 

 becomes acid, it must be neutralized, before evaporation, by a little 

 carbonate of barytes. 



Hypophosphite of Potash. — This salt was prepared by the double 

 decomposition of hypophosphite of barytes and sulphate of potash. 

 The aqueous solution was evaporated to dryness, and the residue, 

 treated with hot alcohol, deposited hypophosphite of potash on 



