316 Intelligence and Miscellaneous Articles. 



washed and dried it may be reduced by hydrogen in the manner above 

 mentioned : in this operation water and sulphuretted hydrogen are 

 produced. — Ann. de Chim. et de Pkys., torn. lv. p. 2 10. 



PURIFICATION OF CARBONATE OF SODA. BY M. GAY LUSSAC. 



This salt is commonly purified by repeated crystallization, but it 

 retains so large aquantity of interposed mother liquor that ir.any ope- 

 rations are required to entirely free it from other substances, and 

 after all but a small quantity is obtained. The following process 

 having appeared to me extremely advantageous, I think it may be 

 useful to make it known. 



This process is analogous to that which is followed in France for 

 purifying nitre. It is as follows : — Take the crystals of carbonate of 

 soda, such as are met with in shops; having washed them, make a sa- 

 turated hot solution ; when this is set to cool, stir constantly with a 

 rod or spatula to disturb the crystallization and to obtain small crystals 

 resembling sand : the cooling may be accelerated by placing the ves- 

 sel containing the saline solution in cold water. It sometimes hap- 

 pens that when very much cooled the solution does not crystallize, 

 and that it suddenly becomes solidified. This is the moment to stirvery 

 rapidly, to prevent the conglomeration of the crystals. This delay in 

 the crystallization may be prevented by throwing a few crystals into 

 the solution at the moment when it begins to be supersaturated. 



Having obtained the crystals, put them into a funnel, in the neck 

 of which place a little tow or cotton to retain them. At first let them 

 drain, then wash them with small quantities of distilled water, waiting 

 till the preceding washing has run through. Test from time to time 

 the washings with nitrate of silver, the washing being previously satu- 

 rated with pure nitric acid : the purification of the salt is complete 

 when the liquid remains transparent. By this process, and in the first 

 operation, the greater part of the carbonate of soda employed may be^ 

 obtained in a perfectly pure state. The mother liquor and the wash- 

 ing may be evaporated and treated in the same manner. The same 

 mode of purifying may be used with advantage for many other salts. 

 Its 'efficacy is founded upon the extreme facility with which water 

 runs through and well washes sandy crystals, such as are obtained 

 by disturbing the crystallization. —^wn. de Chim. et de Phys., tom.lv. 

 p. 22 1 . 



FOSSIL WAX OF MOLDAVIA. BY M. MAGNUS. 



This substance is evidently a mixture of several different matlers. 

 It is indeed true that this is not immediately seen, for though it has 

 sometimes the fibrous structure of amianthus, and is sometimes con- 

 choidal in its fracture, it yet appears to be homogeneous; if, however, 

 one of the small leaves of which it is composed be carefully examined, 

 small deep coloured points are visible. When the fossil wax is boiled 

 with even absolute aether or alcohol, but a very small quantity is dis- 

 solved, whilst the greater part of the remaining portion has an eaten 

 appearance, which shows that the mass is composed of two substances, 



