CHEMICAL SCIENCE. 261 



potassium, changes sulphate of protoxide of iron, into bibasic sul- 

 phates and acids, transforms yellow cyanide of potassium into red 

 cyanide, and converts sulphuret of lead into sulphate, etc. The 

 essential oil of turpentine, and that of citron produce the same effects, 

 if treated in the same way. Accordingly to M. Schonbein this new 



/ C^ v 



property is due to the presence of oxygen in an exalted chemical 

 condition. Jour, de Chemie. 



ANALYSIS OF PERSPIRATION. 



THE analysis of perspiration has hitherto given contradictory 

 results to the several analysts who have examined it ; it is still 

 doubtful. M. Favre has, however, presented to the French Academy 

 an important memoir upon this subject, in which he establishes some 

 facts and exhibits results new in the history of secretions. He has 

 isolated from perspiration two immediate principles, whose existence 

 in that liquid was never suspected ; one is urea, a composition found 

 in several other humors, and an azotic acid discovered by M. Favre, 

 and which he calls sudrique acid. Among the elements whose exist- 

 ence remained an object of doubt to physiologists was lactic acid. M. 

 Favre was so skilful and he had so large a quantity of perspiration to 

 operate on (no less than 80 pounds !) he succeeded in obtaining six 

 grammes of lactate of zinc. M. Favre ascertained that the chlorure 

 of sodium, by its large proportion, must be considered as the essential 

 mineral element of the liquid secreted by the sudoriparian glands. 

 The almost absolute absence of other inorganic materials (such as 

 phosphates and sulphates) in perspiration throws new light upon the 

 secreting functions, and proves this singular fact : the saline sub- 

 stances dissolved in the blood are eliminated one to the exclusion of 

 another, by the different glandular apparatus of the system. For 

 example, in analysing two equal proportions of urine and of perspira- 

 tion, 28 pounds of each coming from the same subject, the first gave 

 21 grammes of alkaline sulphates and the second only one decigramme. 



ON A METHOD OF GETTING RID OF SAL-AMMONIAC IN ANALYSIS. 



copy the following communication by Dr. J. Lawrence Smith, 

 from Silliman's Journal, Jan., 1853. There is nothing in mineral 

 analysis more embarrassing than the accumulation of sal-ammoniac 

 towards the end of an analysis, especially where potash or soda are to be 

 estimated. The only method now adopted to get rid of this ammoniacal 

 salt, is to volatilize it by heat, which if the quantity be considerable, is 

 attended by no little annoyance, and a certain loss of more or less of 

 the fixed alkalies which may be present, I have recently discovered a 

 mode of overcoming that difficulty, and much experience has proved 

 its value, the method is simply *to add nitric acid to the solution 

 containing the sal-ammoniac and alkalies, and heat it gently over a 

 lamp or sandbath in a glass flask or porcelain capsule. The nitric 

 acid may be added either before the liquid is eoncentrated, or after 



