io6 



SCIENCE. 



[Vol. XXn. No. 551 



stant stirring, was reduced to a minimum. The addition 

 of the Paris green to the Bordeaux before the emulsion 

 was put in did not visibly affect the mixture. Up to this 

 point, therefore, the combination was a success. It now 

 remained to be seen how it would stand a practical test 

 by the ordinary fruit grower in the field. Theoretically, 

 the chances were all in its favor. 



However, further experimentation at the Insectary 

 showed that unless the Bordeaux was rightly made, the 

 emulsion would not form a stable combination with it, 

 and in fact sometimes would scarcely mix at all. It was 

 found that the best combination was obtained when the 

 acid copper sulphate solution of the Bordeaux was exactly 

 neutralized by the alkaline lime; the potassium ferroey- 

 anide was the test to determine when this point was reached. 

 Thus, when the Bordeaux was made in the usual way with- 

 out testing, nine times out of ten the emulsion would not 

 mix with it satisfactorily. Here, then, was the first obsta- 

 cle to the Cornell mixture, — the difficulty of making it. 



In the spring I saw it made and applied on a large 

 scale, with horse power sprayers. As far as the making 

 and application were concerned, it was a success. It 

 worked as easily through the sprayer and nozzle as the 

 Bordeaux alone. But an examination of the trees after 

 the sprayer had passed showed that the mixture had not 

 spread so evenly over the tree as would either of the in- 

 gredients alone. And right here, I believe, is the weakest 

 point in the Cornell mixture. The spray was thrown fine 

 enough, but when it struck the trees the minute particles 

 seemed to be drawn together into larger oily drops, leav- 

 ing considerable areas unw£t. There is a tendency in the 

 Bordeaux mixture alone to do this, but it was increased 

 by the oil in the emulsion. 



One can easily imagine with what regret I am thus 

 obliged to tear the mask from off my theoretically com- 

 plete panacea. When first concocted it seemed equal to 

 all that might be claimed for it, and it was thought best 

 to publish it at once; but, realizing that it ought to be 

 first fully tested in a practical manner, it was put into the 

 hands of two or three large fruit growers with the re- 

 sults which I have detailed above. On the whole, the 

 Cornell mixture, theoretically, has great possibilities, and 

 in the hands of careful men can be made, but for the 

 ordinary fruit grower or farmer the difficulty of making 

 it will render it impracticable. And when properly made 

 and applied it will be quite effective, each ingredient for 

 the purpose it is intended. But 1 believe the' effective- 

 ness of each ingredient will be greater if they are not 

 applied in combination, but singly. Thus, theoretically, 

 the Cornell mixture has great possibilities, but, besides 

 the difficulty of making, the effectiveness of each ingre- 

 dient is lessened, and in consequence the practicability of 

 the mixture is as yet doubtful, and I cannot freely recom- 

 mend it for general use. 



*To make the Bordeaux mixture, dissolve six pounds of sulphate of copper 

 in four or five gallons of hot water. Slake four pounds of quick lime in suffi- 

 cient water to form a thin whitewash and strain this through a gunny sack 

 (burlap) into the copper sulphate solution. Dilute to forty gallons with 

 water, and the mixture is ready for use. When using, it must be kept thor- 

 oughly stirred to keep the lime in suspension. The preparation of the mix- 

 ture in large quantities may be simplified by a test which obviates the neces- 

 sity of weighing the lime. Keep the mixture thoroughly stirred when the 

 thin whitewash of slaked lime is being poured through the burlap, and add 

 from time to time a drop or two of the commercial potassium ferrocyanide 

 to the mixture. If not enough lime has been added the drop of ferrocyanide 

 will turn to a very dark color the moment it touches the mixture; when 

 enough lime has been added, the ferrocyanide will not change color when it 

 is dropped into the mixture. 



To make the emulsion, thoroughly dissolve one-half pound hard or soft 

 soap in one gallon boiling water. While this solution is still very hot add 

 two gallons of kerosene and quickly begin to agitate the whole mass through 

 a syringe or force-pump, drawing the liquid into the pump and forcing it 

 back into the dish. Continue this for five minutes, or until the whole mass 

 assumes a creamy color and consistency which will adhere to the sides 

 of the vessel, and not glide off like oil. It may now be readily diluted with cold 

 rain water, or the whole mass may be allowed to cool when it has a semi- 

 solid form, not unlike loppered milt. This standard emulsion, if covered 

 and placed in a cool dark place, will keep for a long time. In making a dilu- 

 tion from this cold emulsion, it is necessary to dissolve the amount required 

 in three or tour parts of boiling water, after which cold rain water may be 

 dded in the required quantities. 



CHEMISTEY IN CANE SUGAE MANUPACTUEE. 



BY J. T. CEAWLEY, SUGARLAND, TEXAS. 



During recent years the part jilayed by chemistry in 

 the manufacture of sugar from the sugar cane has become 

 an important one, cane sugar manufacture is older than 

 beet sugar manufacture, but it remained for those inter- 

 ested in the latter to work out the practical and scientific 

 questions that make the industry of such vast imjDortance 

 at the jiresent time. It is only in recent years that the 

 same scientific j)rinciples have been afiplied in tropical 

 countries in the field and in the factory. Important among 

 the recent imj)rovements has been the application of 

 chemistry to the better understanding of the various 

 changes that the raw material may undergo while being 

 converted into refined products. 



When the cane is brought from the fields it is weighed, 

 and then, in most cases, is passed between immense iron 

 rollers where the juice is exj)ressed. By recent improve- 

 ments in mills the per cent of juice actually obtained, has 

 increased from the neighborhood of 65 per cent to from 

 75 to 80 per cent. 



This great imj)rovement has been made of course by 

 the engineer, but it is safe to say that without the aid of 

 the chemist in calling attention to the immense losses in 

 the bagasse these improvements would have been delayed 

 many years. 



After exj)ression the juice is either weighed or measured 

 and then the real work of chemistry begins. Because of 

 the changes that the contained sucrose may undergo dur- 

 ing subsequent processes the juice is analysed for sucrose, 

 glucose, total solids, ratio of sucrose to glucose and ratio 

 of sucrose to the total solid matter. This gives, by 

 proper calculations, the total amount of the various in- 

 gredients entering the factory with the various ratios one 

 to the other. These ingredients with their ratios must be 

 watched very closely to see that impurities are not formed 

 at the expense of the cane sugar. Lime is added to the 

 raw juice for the purpose of neutralizing the acids con- 

 tained therein, and in order to purge it of many of the 

 impurities that would interfere with the subsecjuent 

 crystallization of sugar. Here again a strict watch must 

 be kept. An insufficient quantity of lime leaves free acids 

 in the juice and these same acids will act upon the sucrose 

 changing it into glucose, or inverted sugar, during the 

 evaj)oration of the juice and syrup. Analyses are made of 

 clarified juice, syrup, massecuite, etc., and from these 

 analyses together with the weights of these various pro- 

 ducts the chemist is enabled to detect any important loss 

 that has been sustained, whether it be chemical or 

 mechanical, and from a scientific examination of the data 

 thus furnished the manufacturer is enabled to so modify 

 the variolas processes as to get the best results, finally the 

 sugar and molasses are analj'sed, and thus a comjslete 

 record is had of the whole process from the entering of 

 the cane to the final output of sugar and molasses. It 

 will thus be seen that the chemist is the book-keej)er, so 

 to speak, of the sugar during the process of manufacture, 

 and it is his business to point out losses, and, if possible, 

 suggest remedies. It is a rare case, however, to find a 

 factory in Louisiana where a strict chemical control, such 

 as has here been outlined, is maintained. 



The great amount of labor necessary, together with the 

 cost of weighing and measuring apparatus, has prevented 

 the majority of factories from adopting such a complete 

 system as will tell them the efficiency of their work. 

 But in these daj's of sharp competition the fact is gradu- 

 ally impressing itself that science must not be overlooked, 

 and that it is of vast assistance even where money-making 

 is the only end. 



