34 



the absence of other kinds of sugar capable of fermentation, which 

 is a rare case. When other fermentable sugars are present, they 

 may be destroyed by heating with an alkali (hydrate of lime), 

 afterwards the whole has to be acidified again and mixed with 

 yeast. 



2. By treating with an alkaline solution of tartarate of copper. 

 — The mode of operation is similar to that indicated under Starch, 

 i.e., convert the cane-sugar into grape-sugar by heating the respec- 

 tive substance for two hours with water containing 2°/^ sulphmic 

 acid, saturate the acid liquid (cold) with soda-ley and determine 

 the amount of the grape-sugar by means of the copper solution. 

 One hundred parts grape-sugar, as found by the above method, 

 correspond to 95 parts cane-sugar. If, besides the cane-sugar, 

 other kinds of sugar be present which directly i-educe the solution 

 of copper, the latter have to be determined first ; afterwards a 

 new portion has to be treated with acid and the whole of the 

 sugar estimated as above. The first quantity, when subtracted 

 from the second, will represent the amount of cane sugar, converted 

 into grape-sugar by the acid. 



CaolltcllOUC^Cio H32. It is probably contained in every milky 

 juice of plants but has been obtained on a large scale chiefly 

 from Hevea elastica, Castilloa elastica, C. Markhamiana, Han- 

 cornia speciosa, Urceola elastica, Vahea Madagascariensis, Y. 

 Comorensis, V. g-ummifera, Y. Senegalensis, Landolphia Owariensis, 

 L. Heudelotii, L. florida, Willoughbya edulis, W. Martabanica, 

 Ficus macrophylla, Ficus elastica and some other species of these 

 genera. The commercial india-rubber is purified by dissolving in 

 chloroform and precipitating with alcohol. White and opaque as 

 long as it contains water in its pores, but colourless and trans- 

 parent after prolonged drying at the atmosphere, only in thicker 

 layers of a yellowish coloiu- ; elastic ; without taste and smell ; 

 fuses at 160° and decomposes in higher temperatures; does not 

 dissolve in water, but swells up in hot water and becomes sticky; 

 insoluble in acids and in alkalies; swells up in cold and more so in 

 boiling alcohol without dissolving, dissolves only partly in sulphide 

 of carbon and in anhydrous ether (to about two-thii-ds), readily and 

 completely in chloroform. 



Capric Acid = 020 H19 O3 -f HO. In the oil of the Cocoa- 

 nut (;b'ee Caproic Acid). OnS hundred parts by weight of the 

 Caprate of baryta, consisting of scales of fat-lustre, are decom- 

 posed by a mixture of 47 "5 parts concentrated suljihuric acid 

 and 47 "5 parts water, and the separated fat-acid crystallised 

 in alcohol. — White mass, consisting of fine needles, of a faint 

 goat-like smell, similar to caproic acid, of an acid, burning and 

 disagreeable taste; has a density of 0-910, ftises at 30 to 46°, boils 

 above 100° and volatilises without decomposition, dissolves in 1000 



