224 Miscellaneous Intelligence. 



at which a solution of sulphate of soda is evaporated, 'will cause 

 the formation of hydrated or anhydrous crystals at pleasure, and 

 that whether the quantity of the solution be large or small. This, 

 indeed, might have been expected from that which takes place 

 when hydrated crystals of sulphate of soda are carefully melted ; a 

 portion dissolves, and a portion separates, the latter in an anhydrous 

 state*. I find that, if it were desirable, crystallized anhydrous sul- 

 phate of soda might easily be prepared for the market; though, as 

 the pure salt is now but little used, it is not likely this condensed 

 form will be required. Whenever a soda salt is to be distinguished 

 from one of potash, in the manner above described, this elfect of 

 temperature nnist be carefully guarded against. — M. F. 



7. Habitudes ofSulpMiricAcid. — M. Bellani found that the glacial 

 sulphuric acid of Nordhausen, like common concentrated sulphuric 

 acid, had a specific gravity of 1.843 at 50° F. and that it congealed 

 at 53°.6. When it was exposed to air, at nearly a freezing tem- 

 perature, the surface absorbed water and became covered with 

 crystals, which, when separated and fused, gave a liquid of s. g. 1.78. 

 On the other hand, when glacial acid was mixed with enough 

 water to give a fluid of s. g. 1.793, it, when frozen, supplied crystals 

 which, being melted, gave a liquid of s. g. 1.78, whilst the residual 

 liquid had a s. g. of 1.73. 



When sulphuric acid, concentrated or diluted, congeals, it under- 

 goes a diminution of volume, almost equal in extent to the increase 

 which takes place with water under similar circumstances. Thus, 

 1000 parts of fluid glacial acid become 92.5 parts by volume of sohd 

 acid; and 1000 parts of acid of s. g. 1.78, by congealing, become 

 910 parts, from which it would appear that the water in the diluted 

 acid does not undergo the same change in solidifying, as when in 

 the free sizLie.^ Giorncde di Fisica — Bull. Univ. A. viii. 316. 



8. On lodo-fluoric Acid, by M. J. Varvinsky. — On mixing va- 

 pours of iodine and fluoric acid in a glass globe, the latter 

 became lined with a white film, and the iodine was absorbed ; when 

 the action appeared to have ceased, water was poured into the 

 globe and caused an immediate deposition of gelatinous silica. By 

 filtration, a liquid was obtained, yellow from free iodine, but be- 

 coming colourless by heat ; carbonate of ammonia was then added 

 in excess, which separated the rest of the silica, and carbonic acid 

 gas was disengaged. The filtered solution was very alkaline, but 

 by ebullition gradually became quite acid. Being afterwards cooled, 

 it deposited many small crystals of a fine golden yellow colour, and 

 possessing all the properties of a strong acid. They dissolved more 

 readily in hot than in cold water, and, with caustic potash, pro- 

 duced a gelatinous salt, having a very disagreeable bitter taste. 

 These crystals are the substance which I have called iodo-fluoric 



* Quarterly Journal, xix. 153. 



