— 121 — • 



Many years ago we criticised the citral estimation with hydroxylamine 

 hydrochloride described by Walther 1 ), which at the time gave no good 

 results when we submitted it to a control-test. Neither did the alteration 

 proposed by Bennett 2 ) lead to any satisfactory results. According to 

 H. C Fuller 3 ), it is possible to use the hydroxylamine method for estimat- 

 ing the camphor-content of spirits of camphor. He dilutes 25 cc. spirits 

 of camphor with 2 g. carbonate of sodium in a 100 cc. flask. Next he 

 adds from a burette 35 cc. of a solution of 20 g. hydroxylamine hydro- 

 chloride in 30 cc. water and 125 cc. absolute alcohol free from aldehyde. 

 The mixture is heated for two hours in a reflux-condenser to a gentle 

 boiling-temperature, cooled down to 25°, diluted with a mixture of 6 cc. 

 hydrochloric acid (sp.gr. 1,12) and 6 cc. water and again diluted to half 

 a liter. The free mineral acid is then neutralised in 55 cc. of this liquid, 

 methyl orange being employed as an indicator, after which phenol- 

 phthaleine is added, and the hydroxylamine hydrochloride is titrated back 

 with decinormal soda liquor. At the same time a blank test is prepared. 

 The difference between the two titrations corresponds to the quantity of 

 camphor oxime which has been formed. 1 cc. decinormal soda liquor 

 = 0,01509 g. camphor. No particulars are given of any results obtained 

 by this method, and a control-test made by us has given no satisfac- 

 tory results. 



In our last Report we made mention of a method for the determination 

 of hydrocyanic acid described by L. Rosenthaler 4 ) and based upon the 

 conversion of this acid by means of mercuric chloride into mercuric cyanide 

 and hydrochloric acid. Another method devised by the same author 5 ) is 

 based upon the conversion of hydrocyanic acid with mercuric nitrate, 

 according to the equation: Hg(N0 3 )2 + 2HCN = Hg(CN) 2 + 2HN0 3 . The 

 excess of mercuric nitrate is titrated with ammonium sulphocyanide solution 

 (using ammonium ferrisulphate as an indicator). For this determination 

 a decinormal mercuric nitrate solution, a decinormal ammonium sulpho- 

 cyanide solution, and a saturated ammonium ferrosulphate solution slightly 

 diluted with nitric acid are required. The liquid containing hydrocyanic 

 acid is allowed to run into the excess of solution of mercury, whereupon 

 the titrating-vessel is closed and vigorously shaken. Whether sufficient 

 mercuric nitrate has been added is shown by the absence of hydrocyanic 

 acid odour in the liquid. Saturation of the liquid with chlorine-free alkali 

 nitrate produces more clearly-defined reactions. 1 cc. decinormal Hg(N0 3 )2 

 = 2,7018 mg. HCN. 



l ) Pharm. Zentralh. 40 (1899), 621 ; 41 (1900), 614; Report April 1900, 22; October 1901, 26. 



J ) Comp. Report April 1909, 110; October 1909, 153. 



*) Oil, Paint and Drug Reporter 80 (1911), No. 7, p. 39. 



*) Report April 1911, 153. 



•') Arch, der Pharm. 249 (1911), 253. 



