156 



Manufacture of Sugar from Beet- Root. 



them ; the free organic acids are neutralised ; and, consequently, 

 all the salts held in solution by them (malates, phosphates, &c.) 

 are precipitated, most of which, save the alkalis, are decomposed, 

 and insoluble salts of lime formed: the fatty and colouring 

 matters, to a great extent, are also destroyed. If an excess of 

 lime be left, it combines readily with an equivalent of the sugar, 

 and forms a distinct compound, which is afterwards decomposed 

 in the decolorizing operation. Achard recommends that this 

 excess of lime should be at once taken up by sulphuric acid ; 

 this compound is, however, by many considered to be more pre- 

 judicial to the sugar than the other compound. Kiihlmann, 

 instead of sulphuric acid, takes up the excess of lime by carbonic 

 acid. The various compounds resulting from the mixture of 

 lime with the juice at a high temperature, are removed either in 

 the shape of a scum from the surface, or by decanting the clear 

 syrup from the dregs occasioned by the precipitation of those 

 that were insoluble. In boiling, the liquid should be of a clear 

 yellow colour : if the boiling commences in the middle before 

 the sides, it is considered a bad sign ; and the scum should be 

 thick and tough, and full of irregular fissures. The refuse of 

 the clarifying pans of one of the large factories, at Magdeburg, 

 was examined by Schmidt, who found it to consist of albumen, 

 azotized matters resembling gelatine, others resembling humus, 

 a soap formed of lime and fatty substance, oxalate of lime, 

 phosphate of lime, sand. Sic. It is very desirable to ascertain, as 

 near as possible, the proportion of lime to be added to the juice ; 

 as, although an excess does no direct injury, it may occasion some 

 loss in the produce. However, this must in most cases depend 

 upon the condition of the syrup, whether it is made from per- 

 fectly sound roots or not, and the period of the season. If the 

 roots are sound and fresh from the soil, then less lime is required 

 than if they had been at all injured, or stored away for any time. 

 In the former case, about 3 to 5 parts of lime to 1000 parts of 

 juice are sufficient ; in the latter, from 5 to 10 parts to the 1000, 

 according to the requirements of the case. Some care is needed 

 in the preparation of the lime, which must be carefully slaked 

 (hydrated) by mixing it with about 10 parts of boiling water, 

 and then passing it through a fine wire sieve, so that all impu- 

 rities and lumps may be separated. When the clarification is 

 completed, the syrup is removed as hot as possible to the filtering- 

 room, Avhere it is passed through layers of animal charcoal in the 

 ordinary way. This operation is usually repeated, the syrup being 

 evaporated to a greater density previous to the second tiltration. 



These two operations remove any impurities that may have 

 passed from the clarifying pans, the excess of lime, and all the 

 colouring matter of the syrup. The only portion of the process 

 now left is to concentrate the decolorized syrup, and then run it 



