480 hitelligence and Miscellaneous Articles. 



the skin and lungs a more direct way for its exit from die or- 

 ganism than the kidneys. 



Experiments for the determination of the amount of am- 

 monia in the urine of healthy individuals may become of im- 

 portance in judging of pathological states; for in fevers, and 

 other diseases, the amount of ammonia in the urine increases 

 considerably. It is possible that, by analysing the urine, we 

 may, in the increasing or decreasing amount of ammonia, ob- 

 tain a measure for the alterations which take place in diseases. 

 But the salts of potash, which are rarely absent, as well as the 

 ammonia which is formed by the action of chloride of platinum 

 upon the organic constituents of urine, render this reagent 

 (the chloride of platinum) very unsafe for determining the in- 

 creasing or decreasing amount of ammonia in the urine during 

 disease. The magnesia salts would perhaps answer this pur- 

 pose better; the quantitative examinations made with salts of 

 magnesia are inferior to those made with chloride of platinum, 

 but they are exact enough for the purpose of comparison. 



LXXVII. Intelligence and Miscellajieous Articles. 



ON THE ESSENTIAL OIL OF BETULA LENTA AND ON GUALTHE- 

 RINE. BY W. PROCTER. 



THE author has found that the essential oil, which is obtained 

 by the distillation with water of the Betula lenta (sweet birch 

 or mountain mahogany), which is so common in North America, 

 and which gives to some of its flowers their agreeable odour, v/hich 

 resembles that of gualtheria oil, is identical vfiih. the latter; but that 

 the bark evolves this odour only when in contact with water, wliiist 

 originally it contains an inodorous body only, viz. gualtherine, which 

 is converted into the essential oil when water is present, by the reac- 

 tion of another substance also present (analogous to synaptase or 

 emulsine), exactly as the oils of bitter almonds and mustard are 

 formed. 



By the action of barytic water, this gualtherine yields a new acid, 

 the gualtheric acid. Unfortunately the author has not made use of 

 elementary analysis. 



Oil of Betula lenta. — This oil smells and tastes like gualtheria 

 oil, has a specific gravity of I*] 73, becomes reddened by the action 

 of the atmosphere, but loses the colour on distillation ; is but little 

 soluble in water, in all proportions in alcohol and aether ; produces 

 a purple-red colour with protosalts of iron ; forms crystalline com- 

 pounds immediately with solution of potash, soda, baryta and oxide 

 of lead ; these yield the oil unaltered when treated with dilute sul- 

 phuric acid ; when treated with excess of potash, salicylic acid is 

 formed ; it is slowly dissolved by ammonia, and the solution deposits 

 crystals of salicylamide. Crystalline products are obtained by the 

 action of chlorine and bromine, hydrochloric and bromic acids being 



