Intelligence and Miscellaneous Articles, 71 



been described, possesses the properties of white of egg, but not 

 those of cheese j and Payen and Henry, who had considered the re- 

 sults obtained by Soubeiran as opposed to theirs, are convinced by 

 new trials, that this principle cannot be considered as caseum, but 

 that it ought to be called albumino-caseous. I add, that according to 

 its properties, it is rarely identical with vegetable albumen. — Ibid. 



BERZELIU8. 



ANHYDROUS CRYSTALS OF SULPHATE OF SODA. 



In the Number for April of the Royal Institution Journal, Mr. Faraday 

 makes the following observations with respect to this salt : — If a drop 

 of a solution of sulphate of soda be placed upon a glass plate and al- 

 lowed to evaporate spontaneously, it will leave crystals which may 

 be distinguished by their form and alternate efflorescence as being 

 the salt in question. Most of the potash and soda salts may be dis- 

 tinguished as to their base by such an experiment. They are easily 

 converted into sulphates by a drop or two of sulphuric acid and ig- 

 nition j and then being dissolved and tried as above, will yield 

 crystals which may be known by their forms, and more especially by 

 their efflorescence if of soda, and their unchangeable state if of potash. 

 This test is, however, in some circumstances liable to uncertainty, 

 arising from a curious cause. If the drop of solution on the glass be 

 allowed to evaporate at common temperatures, then the efflorescence 

 takes place, and the distinction is so far perfect j but if the glass plate 

 with the drop upon it be placed upon a warm part of a sand-bath or 

 hot iron-plate, or in any other situation of a certain temperature con- 

 siderably beneath the boiling point of the solution, the crystals which 

 are left upon evaporation of the fluid are smaller in quantity, more 

 similar in appearance to sulphate of soda, and finally do not efflo- 

 resce. Upon examining the cause of this difference I found they 

 were anhydrous, consequently incapable of efflorescing, and indeed, 

 exactly of the same nature as the crystals obtained by Dr. Thomson 

 from certain hot saturated leys. — Ann. Phil. N. S. xx. 201. 



Hence it would appear, that a mere difference in the temperature 

 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 what takes place when hydrated 

 crystals of sulphate of soda are carefully melted j a portion dissolves, 

 and a portion separates, — the latter in an anhydrous state. (Quarterly 

 Journal, xix. p. 153.) I find that, if it were desirable, crystallized an- 

 hydrous sulphate of soda might easily be prepared for the market 5 

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

 condensed form will be required. Whenever a salt of soda is to be 

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

 effect of temperature must be carefully guarded against. 



CASEOUS OXIDE, AND CASEIC ACID. 



The results obtained by Proust relative to the substance produced 

 by the fermentation of cheese, have been described and examined by 



M. Henri 



