[26] "Preparation and Vulcanisation of Plantation Para Rubber" (Eaton, Grantham, and Day), Bulletin No. 27, F.M.S. Department of Agriculture; Gorter and Swart, Bulletin No. 6, West Java Expt. Station. (_a_) As a direct coagulant. (_b_) In its action upon certain organisms which, in the ordinary course of events, would delay or prevent coagulation. Although work on an experimental scale has been done, as far as we know no practical application has been made of the employment of sugars as coagulating agents. VARIOUS SALTS.--Of experimental interest only it may be recorded that coagulation has been effected by means of various chemical "salts"--_e.g._, calcium chloride, barium chloride, magnesium chloride, sodium chloride, aluminium sulphate, magnesium sulphate, sodium sulphate, etc. None of these has been found to have any practical application, except, perhaps, calcium chloride, which is used in small quantity as an accelerating agent in a special process of anaerobic coagulation, which will receive mention in the following chapter. At one period during the War and the dearth of acetic acid, it was found that there were available in England large supplies of the acid sulphate of sodium (sodium hydrogen sulphate), which proved to be an effective coagulant. Experimental work gave satisfactory results, but no practical application resulted when supplies of acetic acid were again obtainable. VARIOUS PROPRIETARY COMPOUNDS.--We have seen many proprietary coagulants advertised and pass into the limbo of forgotten things. They can generally be divided into two classes. The first embraces those founded upon a woefully incomplete knowledge of requirements. The second covers those which meet requirements, but for which exaggerated claims are made and excessive prices charged. As as instance of a substance which fell under both classifications might be mentioned the case of "Coagulatex." Pretentious claims were made, and it was emphasised that the liquid contained no _vegetable acids_. Acetic and formic acids might be quoted as examples of vegetable acids, and as these have been shown to be the most satisfactory coagulants now employed one fails to imagine where lay the value of the guarantee given by the advertisers of "Coagulatex." On analysis the liquid was found to consist mainly of sulphuric acid, against the indiscriminate use of which warnings have been given. Thus it was a dangerous substance for common use. Furthermore, comparing the value with its sulphuric acid content, it was found that the price required for "Coagulatex" was roughly four times the contemporary cost of commercial sulphuric acid in the Federated Malay States. Those in charge of estates should realise, therefore, that no proprietary coagulants should be adopted until a proper report of tests, and a comparative valuation, has been obtained from one of the research laboratories.