In using volatile alkalis, which are nevertheless falling into disuse more and apparently no longer maintain their reputation, ordinary ammonium carbonate which may be easily obtained in powder form at any chemist’s, or a solution of ammonia, such as spirits of sal-ammoniac, may be used. The former is easily soluble in about five parts of water. From ½ to 3 kilograms of ammonium carbonate are generally reckoned for every 100 kilos of undefatted cacao material, and this amount is dissolved in water, the whole of the salt being at once introduced into from 15 to 30 litres, as when smaller quantities are used there ensues a decomposition of the salt and one of the products of decomposition, the carbonate of ammonium, remains undissolved. The spirits of sal-ammoniac operate much more effectively than the ammonium carbonate on account of their high percentage of ammonia, and so only a third as much of this substance may be employed, and generally even smaller quantities prove quite sufficient. Consequently 100 kilos of defatted cacao should be mixed with 0·5-1 kilo of ammonia solution (specific gravity 0·96), previously diluted with 20 or at the most 29 litres of water. The mixture should be prepared in glass carboys immediately before use, because of the volatility of ammonia. In the treatment of the cacao, salt solution and cacao are together introduced into a melangeur, or better into the kneading and mixing machine, and the apparatus being set in working order, steam enters, and removes the quantities of water which have been added, as well as the volatile alkalis. Whether all the water has been driven off or no can only be judged from the consistency of the mass after treatment, and it is just this that renders the process of little value. The cacao material issuing from the machine must be just as liquid as when it comes out of the triturating mills, and so long as it appears as a glucose substance, which very often happens where unsuitable mixing machines are employed, so surely will it contain water, and this may lead to the growth of mould or to the cacao developing a grey colour when packed in boxes. If the cacao cannot be sufficiently dried in these machines, it must be transferred to some sort of drying plant (where the temperature is about 48 ° C.), and there deprived of its still remaining moisture. When volatile alkali is used, kneading and mixing machines cannot very well be dispensed with, as they work up the cacao material much more thoroughly and admit of a better distribution of the ammonia than the melangeur or incorporator. In this case it is advisable that the entire process be carried out in some apartment separated from the other rooms of the factory, in order that the pungent smell of ammonia may not be communicated to other products, a further evil connected with this method of disintegration. At the same time provision must be made for the escape of the discharged gas through flues leading out into the open air.[131]