DETECTION OF CANE SUCAR. 103 



similar method, but invert and polarise at 86°, at which tem- 

 perature inverted cane sugar reads 0° ; the method is, however, 

 less convenient than that of Harrison. 



The addition of phospho-tungstic acid to the acid mercuric 

 nitrate filtrate (p. 95), gives slightly higher and more correct 

 results, and should not be neglected with condensed milk. 



Other Methods. — An approximation to the percentage of 

 cane sugar can be obtained by determining the total polarisation, 

 and deducing the milk-sugar by multiplying the ash byG'o, oi 

 the aldehyde figure by 0-24. This method serves for controlling 

 the preparation of condensed milk, but is of course of only 

 approximate accuracy. 



Another method, which gives fair approximate results, is to 

 culeulate the solids not fat (a) from the specific gravity and per- 

 centage of fat, (6) from the percentage of ash by multiplying by 

 12, or the aldehyde figure by (yii. Thu'cane sugar will be repre- 

 , sented by a — b. If the original milk is available the ratio 

 between the solids not fat and the aldehxde figure may be 

 determined, and this figure substituted for (i-M. 



Cotton's Method of Detecting Cane Sugar. — Cotton ;,'ives 

 the following test for cane sugar in milk : — 10 c.c. of the milk 

 are mixed with 0'5 gramme of powdtned ammonium molybdate 

 and U) c.c of dilute hydrochloric acid (1 : Id). In a sceond tube 

 10 c.c. of milk of known purity, or 10 c.c. of a 6 per cent, solu- 

 tion of lactose, are similarly treated. The two tubes are placed 

 in the water-bath and the tenipeiature giadually raised. \t 

 about 80 C. the milk, if adulterated with saccharose, assumes 

 an intense blue colour, whilst the genuine milk, or solution 

 of lactose, remains practically unaltered. On boiliiiL;, these 

 also turn blue, but to a less extent than the adulterated milk. 



This test will detect O'l per cent, of cane sugar, but if this 

 substance be added to milk, larger quantities are almost invari- 

 ably addeil. 



De Koningh modifies Cotton's test by adding 2 c.c. of a satu- 

 rated solution of ammonium molybdate and 8 c.c. of acid (1 : 8) 

 to 10 c.c. of milk. The test tube is gradually heated to 80° C. 

 (not higher), and kept for five minutes at this temperature. 



W. H. Anderson has recently recommended Cayaux's test 

 for cane sugar ; this consists in adding to 15 c.c. of milk 1 c.c. 

 of hydrochloric acitl and O'l gramme of resorcinol. On boiling 

 a red colour is produced in the presence of cane sugar; 2 per 

 cent, is detected by this test. 



Lefimann and Gawalowsky later employ the reaction with 

 sesame oil and hydrochloric acid to test for cane sugar. 1 c.c. 

 each of sesame oil and hydrochloric acid are mixed with a little 

 of the filtrate produced by adding strong hydrochloric acid to 



