June, 1909.] 



513 



Saps awe? Exudations. 



The same result—that is, complete separ- 

 ation of the rubber from the water and 

 latex mixture— can beiobtained by allow- 

 ing the latexto stand for a period of two 

 to six hours after adding the ammonium 

 sulphate solution, without heating ; but 

 the saving of time warrants the use of 

 heat. 



The rubber can also be coagulated by 

 adding acetic acid without the use of 

 heat. After adding the acid the mix- 

 ture should be churned or stirred. 



A very pure quality of rubber can be 

 produced by the use of ammonium sul- 

 phate, because this salt precipitates the 

 proteids, the proteids being compounds 

 very liable to lapid decomposition. 

 However, from the manufacturer's 

 standpoint, it seems to be immaterial 

 whether the rubber is free from pro- 

 teids aud other impurities. 



Sulphuric acid is also a coagulant, but 

 it should only be used in very dilute 

 solutions, 



Formalin may be used in conjunction 

 with either ammonium sulphate, acetic 

 acid, or sulphuric acid. When present 

 in large excess, especially in the presence 

 of ammonium sulphate, it has a rapid 

 coagulating action. While the rubber 

 produced by its use is of very high 

 quality, the formalin preventing de- 

 composition of the finished product, this 

 compound is as yet too expensive for 

 general plantation use. 



Rubber may be obtained from the 

 water and latex mixture without the 

 use of ammonium sulphate by churning, 

 by adding either acetic or sulphuric 

 acid, with or without heat, or by simply 

 allowing the liquid to stand until 

 putrefaction begins. 



One of the advantages of the collection 

 of latex by means of water trickled over 

 the wounds is the possibility of pro- 

 ducing a product entirely free from 

 bark, earth, twigs, and other gross 

 impurities and adulterants. Where rub- 

 ber has been collected from wild trees 

 the common method has been to simply 

 slash the trunk aud branches, permit- 

 ting the latex to flow down them or 

 fall upon leaves placed upon the ground 

 beneath the tree. This method is a 

 very wasteful one, and the rubber thus 

 obtained is of uniformly low value be- 

 cause of the amount of dirt and other 

 impurities. This method is not at all 

 adapted to modern plantation condi- 

 tions. 



Every effort should be made to produce 

 rubber of the purest and best quality ; 

 and it is believed that such rubber 

 can best be produced from the Ceara 

 tree by the use of considerable quantities 



65 



of water in all of the processes connected 

 with the collection and coagulation of 

 the latex, 



A Method of Germinating Ceara 

 Rubber Seeds. 



A new and rapid method of germin- 

 ating Ceara rubber seeds, perfected at 

 La Zucualpa Botanical Station (Mexico), 

 is described by Dr. Pehr Olsson-Seffer 

 as follows : — 



Place a layer of fresh horse manure in 

 a box, to the thickness of about 6 inches, 

 spread the seeds on the surface and 

 cover with about one inch of the same 

 material mixed with a small quautity 

 of sand. The soil should be slightly 

 packed and the box covered with glass. 

 If put in a warm place or in the sun, 

 germination will take place very quickly. 

 The seedlings should be planted as soon 

 as they are an inch or two high and 

 some manure added to the soil. After 

 such treatment the seedlings will grow 

 very rapidly. In planting at stakes the 

 holes should be made as large as pos- 

 sible, or at least 4. feet square. The soil 

 should be well weathered, and if too 

 sour, some lime should be added before 

 planting. 



REVOLUTION IN THE LAC 

 INDUSTRY. 



(Prom the Indian Trade Journal, 

 Vol. XIII., No. 159, April 15, 1909.) 

 There was a time in the not distant 

 past when the sole value of lac depended 

 upon the amount of colouring matter it 

 contained ; but, thanks to the introduc- 

 tion of aniline dyes, its value now 

 largely depends on the entire absence of 

 colour. In other words, hundreds of 

 years ago lac established for itself a 

 position amongst the world's commercial 

 products as a valuable dyeing agent ; 

 to-day there is an ever-increasing de- 

 maud for it owing to its value in the 

 varnish, chemical, electrical, and a host 

 of other trades. It is admitted on all 

 sides that the methods in vogue of pre- 

 paring lac for the market are— as they 

 were centuries ago — crude, slow ana 

 wasteful. All efforts to improve them 

 have hitherto failed, but this failure 

 perhaps is not to be wandered at as, 

 considered from a scientific point of 

 view, we know very little about lac. It 

 is generally defined as a resinous incrus- 

 tation secreted on the twigs of certain 

 species of trees by an insect belonging 

 to the scale insects and known as lachar- 

 dia lacca, or the lac insect. The changes 

 by which the lac is produced do not 

 appear to have been systematically in- 

 vestigated : but this may not be alto- 



