CHEMICAL SCIENCE. 169 



required for purification became perfectly innocuous. In the latter 

 operation, the lime employed caused the bisulphite to disappear by 

 neutralizing it, leaving the juice purified and free from fermentatives, 

 and from all matters capable of producing them. The juice thus pre- 

 pared was ready for evaporation without any loss of sugar. 



" But the bisulphite of lime was soon discovered to possess other 

 qualities of a peculiar character. With the antiseptic property, and 

 the property of absorbing the oxygen gas of air, it unites the proper- 

 ties of a powerful purifier. Heated to 100, French measurement, it 

 separates the albumen, the caseine, and matters containing nitrogen, 

 all of which are found to exist in a natural state in saccharine juice. 

 The separation is eifected without loss, and without any appreciable 

 transformation of the sugar. It remained to be ascertained how far 

 the bisulphite was effective in opposing the coloring of saccharine 

 liquids. The coloring of the saccharine juices of the cane proceeds 

 from four principal causes: 1. The cane itself contains colored matter, 

 which becomes dissolved in the juice. 2. The contact of the juice 

 with the air rapidly engenders colored substances, which unite with the 

 preceding. 3. The heat employed in evaporating, by altering a part of 

 the sugar and of the products which accompany it, also forms color- 

 ing matter. 4. The contact of the air and of the lime, and also of 

 the ammoniacal gases, assisted by the action of the heat, produces 

 coloring matter during the evaporation of the juices when alkalized by 

 lime. 



" The bisulphite of lime almost instantaneously extracts the color of 

 the colored matter which exists in the cane from natural causes ; it 

 prevents the formation of the colored matter which the air produces 

 by its contact with the juice ; and prevents the production of that which 

 is engendered during evaporation, and especially of that which 

 requires for its formation the concurrence of the air and of a free 

 alkali. The effect attending the use of the bisulphite, as an agent 

 capable of resisting the formation of color, is so remarkable as to de- 

 serve the attention of persons employed in many branches of the pro- 

 ductive arts. There is no doubt that the cases are numerous in which 

 it can be employed in the most efficacious manner, in preventing the 

 formation of those coloring matters, which, when once formed, it is 

 found so difficult to destroy or extract. Such matters, for instance, 

 are those which color hemp-yarn and flax, indigo after precipitation, the 

 juice of barks used in tanning, and the extracts of certain dye- 

 woods. 



.Meanwhile, Melsens has established that, in the process of evapor- 

 ating without the application of artificial heat, the presence of the bi- 

 sulphite effectually opposes the formation of coloring matter, and that 

 where the evaporation is effected by the application of artificial heat, the 

 coloring matter formed is scarcely perceptible. 



" Although we have omitted many details, we have exhibited enough 

 to show that bisulphite of lime can be employed in the operation of 

 extracting sugar from the cane, 1. As an antiseptic of superior ex* 

 cellence, preventing the production and action of fermentatives of 

 whatever kind. 2. As an agent absorptive of oxvgen, capable of 



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