Some estates make up a stock solution of 1 part acid to 20 of water, and use this with success because of the fair amount of added water present in the latex. It must be understood that what is being referred to now is not the absolute quantity necessary for coagulation, but the proportions--_i.e._, the respective volumes of acid and water in the solution of acid made up every day. That the strength of the acid solution, as well as the quantity used, has an effect upon coagulation can be easily demonstrated in the following way: Take separate and equal lots of the same latex, and to each add the same quantity of pure acid, but in each case diluted with varying quantities of water. It will be found that coagulation is quickest where pure acid is employed, and slowest where the acid is most dilute. It will also be found that, providing the quantity of acid employed was sufficient for coagulation, the best and most uniform coagulation is obtained from the use of the most dilute acid, within limits. It will often be found that where pure acid has been employed coagulation is local--_i.e._, we have lumpy coagulation, and often a very milky remaining liquor. This is due to the fact that, as coagulation is immediate upon the spot which is first touched by the pure acid, a deal of the acid is enclosed within the rubber at that spot, and hence other portions of the latex are deprived of acid. It is in such cases that most air-bubbles are enclosed. As the dilution of the acid solution is increased the mixing is more thorough and uniform. Coagulation is slower, and air-bubbles can escape to the surface. METHOD OF MAKING STOCK SOLUTION.--Experiments have been repeatedly made in the laboratory with acid solutions of varying dilution, from pure acid down to 1 part of acid in 500 parts of water. While it has been found that a 1 in 5 solution can be used where the latex is very dilute (say, 1 part of latex to 5 parts of water), and a 1 in 20 solution may be used in fairly dilute latex (for crepe-making), it is undoubtedly a fact that for latex as generally "standardised" on estates a much more dilute solution of acid should be used--_e.g._, 1 in 100, or even 1 in 200, of water. It must be borne in mind that the quantity of acid necessary for coagulation is not changed, but merely the dilution. Let us take a concrete case to illustrate the point: On an estate at present the stock solution is made up by diluting 1 pint of acid with 20 pints of water, and 1 gallon of this is necessary to coagulate 50 gallons of pure latex. It is desired to use a stock solution of 1 pint of acid to 100 pints of water. Evidently, therefore, 5 gallons of this stock solution contain only the same quantity of pure acid as 1 gallon of the old solution contained, and it will be necessary to add 5 gallons for every 50 gallons of pure latex. Thus: