On the inside of the cylinder a scale of gallons may be painted, so that one may possess a knowledge of the quantities run into, or required for the completion of, any compartment. A SCREW PLUG UNSATISFACTORY.--It may be of benefit to managers who contemplate such an installation to know that the adoption of a stop-cock in the vent pipe of the cylinder is the outcome of experience. In one instance the vent pipe as designed was fitted with a screw plug at the end. Unfortunately with this arrangement the flow could not be regulated, and owing to the "head" of the latex it dashed violently down the gutter, struck the bottom of the coagulating tank, and thence was scattered over the factory. ANOTHER INSTALLATION.--In another type of installation, in place of the vessels travelling upon a raised verandah platform, the standardised latex is conveyed to the coagulating tanks by means of drums supported by hooks to a chain-block and pulley which travels on an overhead gantry. This method is practicable, but may be regarded as less satisfactory in general working than the verandah method of treatment. A MODERN INSTALLATION.--In the most recent scheme for dealing with the reception of latex, its standardisation, and conveyance to the coagulating tank, the main principle of the first system outlined is retained; but the receptacles are not mobile. Glazed-tile tanks are employed, the capacity of each being approximately equivalent to that of each unit coagulating tank. The accompanying illustrations show the general arrangement and some details of the system of reception tanks employed on the well-known Pataling Estate. CHAPTER VIII _COAGULATION_ Whether it is necessary to employ any coagulant, or whether latex should be allowed to coagulate naturally, will not be discussed at this stage. Neither will mention be made of any patent processes of coagulation which employ other than acid mediums. These subjects will be treated in a subsequent section of the book. CHOICE OF COAGULANTS.--It is not proposed here to enter into a discussion as to the merits of the dozens of known coagulants. Suffice it to state that acetic acid, although the oldest general coagulant, still remains the best and safest at the present time. There is a deal to be said in favour of the use of another organic acid, formic acid. It is equally as safe as acetic acid, and quite efficacious; the only drawback is that, taking all things into consideration, it is very slightly more expensive. Acetic acid, therefore, will always be implied in this chapter when the word "acid" is used. STRENGTH OF ACID SOLUTION.--In the old days it was the rule rather than the exception to find pure, undiluted acid used in coagulation. In many cases no harm resulted, for the simple reason that, owing to the large proportion of water in the latex, the acid was thereby very much diluted. The estates had to thank the over-dilution of the latex for the non-injury of the resulting rubber.