712 



SUGAR. 



as the kind of cane, the soil, climate, season, 

 thriftiness of growth, etc., may still be safely 

 stated at an average of 17 to 20 per cent, of the 

 entire weight of juice in the cane, and, with 

 very rich canes, as high as 21 to 23 per cent. 

 Owing, however, to imperfect conditions under 

 which the process of extraction is carried on, 

 and some of them scarcely avoidable, the amount 

 of pure crystalline sugar in the product secured 

 has thus far, by the old methods, rarely exceeded 

 about 7 per cent, (one-third of that in the en- 

 tire juice of the cane) ; and with many of the 

 improved processes it is not greater than about 

 10 per cent. The two great losses mainly de- 

 termining such results are : first, in the failure 

 to extract the whole of the juice from the canes ; 

 and secondly, in the effect of chemical changes 

 in the juice, in connection, of course, with some 

 necessary loss attending the operations of clari- 

 fying and evaporating. 



It is the nitrogenous matters of the juice (al- 

 bumen and gluten), prone to undergo fermen- 

 tative decomposition, and almost immediately so 

 upon exposure to the air and heat of a tropical 

 climate, which serve very soon to set up chem- 

 ical changes in the liquid. In course of these the 

 proportion of acid present in it rapidly increases, 

 and its color darkens ; while it is stated, indeed, 

 that even in twenty or thirty minutes' time 

 active fermentation would set in. Mr. Fryer, 

 insisting on the unfavorable increase of acid and 

 of color, states that tlie sucrose does not appear 

 to suffer short of several hours ; but in this he 

 is apparently quite at variance with other au- 

 thorities on the question. Before the juice can 

 ferment at all, the change of its cane sugar to 

 grape sugar (unless the latter be already present 

 in it) must have begun ; and any change of tho 

 kind, in cane juice or syrup, eventuates almost 

 certainly either in alcohol and carbonic acid, 

 and then in acetic acid, on the one hand, or in 

 the formation of fructose (molasses) on the other. 



The importance both of neutralizing the acid 

 of the juice and of speedily removing ferment- 

 able matters in it, is now evident. It is usually 

 endeavored to affect both these objects with one 

 agent, as in the operation known as the defeca- 

 ting, and, speaking more generally, the clarify- 

 ing, of the juice. For the process of defecation, 

 which precedes the boiling down or concen- 

 trating, several basic oxides and salts of the lat- 

 ter have at different times, though some of them 

 to a limited extent only, been employed. Among 

 these, caustic lime, which directly neutralizes 

 the acids present, while it is a cheap article, 

 and, properly employed, also harmless, has been 

 thus far in most general use. The lime is 

 usually added in the form of a " cream " or 

 " milk of lime," known as u temper," and to an 

 amount averaging, perhaps, -g^th part of the 

 juice. The coagulating action of the lime on 

 the albuminous matters of the juice is aided by 

 heating the latter, but, until the resulting scum 

 has risen and been removed, not to above 140, 

 or at most 176 F. Authorities generally speak 

 of neutralizing quite the acidity of the juice ; 



but Mr. C. A. Goessmann, of Syracuse, N. Y. 

 (Chemical News, January 20, 1865), in view of 

 the imperfect removal at best of the obnoxious 

 ingredients, favors over-compensating to the 

 extent of securing an alkaline reaction. A great 

 excess of lime is, however, for obvious reasons, 

 to be guarded against. Mr. Goessmann in the 

 same place proposes a plan for concentrating 

 cane juice, involving the use of caustic lime, 

 acid phosphate of lime, and caustic magnesia, 

 and which he believes would result in a gain 

 both in quantity and quality of product over 

 that afforded by the common methods. 



Manufacture of Raw Sugars. This opera- 

 tion, now generally familiar, consists, in its sim- 

 plest form, essentially in expressing the juice 

 of the cut and trimmed canes by crushing be- 

 tween rollers; clarifying and evaporat'ng or 

 concentrating it in a succession of large kettles 

 or pans, into the first of which the defecating 

 agent is introduced, the scum (of coagulated al- 

 bumen and of impurities involved in this) being 

 removed from the first and the succeeding pans, 

 while from the last, the syrup, brought to the 

 crystallizing point, is transferred into coolers, 

 in which it is agitated to promote granulation ; 

 and then removing tho brown pasty mass, of 

 crystals mingled with molasses and remaining 

 impurities, into casks, placed within a large 

 " curing-house," and which are perforated 

 beneath to allow of the draining out of the 

 molasses, this being caught in a large reservoir 

 below. The drained product is a Irown, raw, or 

 muscovado sugar. This, if moist and consider- 

 ably impure, and, especially if containing much 

 saline matter, is still subject to loss in the way 

 of conversion of crystallizable sugar to the un- 

 crystallizable form. 



Improvements in the Manufacture of Raw 

 Sugars. These improvements, as proposed or 

 adopted, have generally had in view one of 

 three objects: 1, to prevent at the outset fer- 

 mentative changes in the juice, and secure its 

 thorough defecation ; 2, to concentrate it with 

 the least possible exposure to conditions favor- 

 ing chemical change, and accordingly, also, at 

 the lowest temperatures sufficing; 3, to secure 

 by other means also, so far as necessary, a 

 purer, whiter, and generally improved quality 

 of product. 



Under the first head may be briefly men- 

 tioned the earlier propositions of Mitchell, to 

 slice the fresh cane and macerate it in hot water 

 with lime, with a view at once to coagulate the 

 albumen and destroy ferment, and to extract 

 the sugar ; of Payen, to defecate the juice with 

 sulphurous acid or bisulphite of lime; of Prof. 

 Daniell, to use subacetate of lead, as purifying 

 more thoroughly and saving a larger percentage 

 of sugar, but which is liable to leave poisonous 

 lead compounds in the product ; and of Dr. 

 Scoffern, to remove the lead salt by means of 

 sulphurous acid. Of these plans, however, 

 none have been used to more than a limited 

 extent, and some, as the first, have been totally 

 abandoned. 



