Spent leys

The mixture is next treated with common salt, which is thrown into the pan by shovelfnlB at a time, each portion being allowed to dissolve in the ley before adding the next. W hen sufficient salt has been added, the saponified matters separate into grains of soap combined with a definite quantity of water, but as yet not containing its full percentage of alkali. The leys, which are called spent leys/ consist of salt and glycerine in solution, and should be quite free from alkali. 

Peorlash added to Combined Soap.—With a view to neutralise the spent leys (salts) contained in combined soaps—that is, curd and hydrated soaps combined, as in Elake and Maxwell s process, or other such combinations Kottula introduces a certain quantity of pearlash, the proportion varying according to the excess of spent leys contained in such combined soap. About 1 cwt. of pearl-ash to 3 tons of soap is said to be sufficient, though a much larger proportion may he used for some soaps ... 

Hr. George Payne s Process.— The inventor takes the spent ley resulting from the manufacture of soap and saturates any free alkali present with an acid. He prefers to use sulphuric, hydrodiloric, or nitric acid. He then takes a solution of tannia or tannio acid, and adds this to the spent ley after being neutraLised by the acid. This solution should contain about one part by weight of tannin or tannio acid to about ten parts by wei t of water. The addition of the solution to the ley is continued until it ceases to precipitate any albuminous or gelatinous matter. 

Thomaa and Fuller s Process.—The spent or partially spent leys are first evaporated until nearly all the salts are deposited the resulting liquor, which is strongly impregnated with glycerine, is then boiled with an excess of fat or fatty acids, which readily combines with the soda salts, and removes all salts which may be in Buspen>< ion in the liquor. The solution is then filtered and sub-... 

It had long been the desire of soap-makers to possess some process of saponification less tedious and costly than the ordinary systems of soap-boiling. It was well own that caustic alkalies would convert into saponaceous matter fats and oils, without the application of heat, and it was also well known that during the process of saponification by the ordinary system of boiling over caustic leys, a considerable amount of glycerine was set free, and which, being a substance soluble in water, passed away with the spent or waste leys, causing a direct and positive loss in the manufacture. 

Having by this means obtained the maximum amount of glycerine in the minimum volume of spent soap leys, the inventor proceeds to evaporate the solution tQl as much salt as possible crystaUises out, when the glycerine is dissolved out from the residue by means of metnylated spirit or other suitable liquid, or the glycerine may be separated by distillation in mcm,... 

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