190 



rubber has really been shipped, as more or les3 shortage invariably 

 takes place. Moreover, the shrinkage in weight is so variable that no 

 exact figures can be quoted by which it may be calculated. The cause 

 being the evaporation of the water contained, it varies according to 

 the quality, being greater in the case of the porous '^Sernamby" than 

 in the firmer Fine" rubber. The longer rubber is kept and the larger 

 the pieces the less it loses in weight. Dry " Sertao" rubber coming 

 from distant parts whence shipments are only made once a year will 

 lose only about 1 per cent, between the estates and Manaos ; where- 

 as newly-made rubber coming from close at hand will lose as much ag 

 10 per cent. As the means of communication get more rapid, and 

 the rubber reaches Manaos sooner after being manufactured, the tendency 

 to lose in weight becomes larger. Between Manaos and foreign 

 markets a loss of 4 per cent, may be taken as an approximation of 

 the average loss in weight. 



A machine designed on the principle of a cream separator to 

 separate the caoutchouc from the watery part has been tried, 

 but has not proved successful as regards the latex of the Hevea, though 

 good results have been stated to have been attained with the latex of 

 the " Castilloa." 



Another means of separating the caoutchouc is to add chemical 

 reagents which cause the latex to coagulate. Of these, acetic acid and 

 corrosive sublimate have been found to give the best results. The 

 latter, owing to its antiseptic properties, would appear particularly 

 suitable. A solution of alum is used to a small extent in the State of 

 Matto Grosso, to prepare rubber from the latex of the Sevea. 



The following analysis of the latex of the Kevea brasiliensis is given 

 by Seeligman : — 



Analj^sis per cent. 



Caoutchouc ... 32 



Nitrogenous matter ... 2*3 



Salts ... 9-7 



Resinous matter ... traces 



Water ... 55 to 56 



ADDITIONS AND CONTRIBUTIONS TO THE 

 DEPARTMENT. 



Library. 

 Europe. 



British Isles. 



Annah of Botany, Sept. [Purchased.] 



Board of Agriculture Leaflets, No3. 64, 65 & 66 [Sec. Board of Agri.] 



Botanical Magazine, Oct. [Purchased.] 



British Trade Journal, Oct. [Editor.] 



Chemist and Druggist, Sept. 22, 29. Oct. 6, 13. [Editor.] 



Foreign Office Reports, July and Aug. 1900. [Col. Sec] 



Garden, Sept 22, 29. Oct. 6, 13. [Purchased.] 



Gardeners' Chronicle, Sept. 22, 29. Oct. 6, 13. [Purchased.] 



International Sugar Journal, Oct. [Editor.] 



