86 



NORTHERN SUGAR INDUSTRY. 



ing, a measured portion of the filtrate was titrated with one- tenth 

 Feh ling's solution. 



In all titrations with copper solutions I determine the end of the 

 process by filtering a few drops of the liquid into a white dish (porce- 

 lain crucible, or lid) in which is previously placed a drop of potassium 

 ferro-cyauide acidified with acetic acid. In order to be exact, the filtra- 

 tion should be as rapid as possible and at a high temperature. 



The only way in which I have been able to secure these two conditions 

 is as follows : A glass tube 10^°^ to 20«"^ in length and 20^^"^ to 30^"^"^ in 

 diameter is softened at one end and pressed on a block of wood. This 

 produces a rim around the end, over which a piece of fine linen can be 

 tied with linen thread. This having been done, the covered end of the 

 tube is placed in a beaker containing asbestos pulp suspended in water* 

 About one-half cubic centimeter of water is sucked into the tube. This 

 leaves the linen diaphragm covered with a film of asbestos. The water 

 is now poured out and the tube is ready for use. When the copper ap- 

 pears reduced, the end of the tube is placed in the dish and a few drops 

 of the liquid sucked into it. This liquid is turned at once into the por- 

 celain dish containing the ferro-cyanide. The end of the reaction can 

 be determined in this way speedily and with the greatest accuracy. The 

 tubes after use are dipi)ed into very dilute nitric acid, and after wash- 

 ing with pure water are again ready tor use. Ten or twenty of them 

 should be kept in working order. 



After having used this method (first more than three years ago) in 

 many thousand determinations, I consider it one of the best means yet 

 devised for indicating the point of exact saturation.* 



ANALYSES OF CANES AND BAGASSES. 



The direct determination of sugars in the canes is attended with many 

 difficulties. The fibrous structure of the canes and their hard points 

 render their reduction to a fine pulp almost impossible. In the follow- 

 ing analyses from 25 to 50 kilograms of the canes and 10 to 20 kilo- 

 grams of the bagasse were passed through the cane-cutter preparatory 

 to sampling. An equal quantity of the canes, as much like the preced- 

 ing as possible, was passed through the experimental mill and the juice 

 subjected to analysis. The details of the operations will be found in 

 the following tables : 



In Table No. 1 will be found analyses of cane chips sampled by the 

 method just described, made as follows: The chips were boiled with about 

 five times their weight of water for a time averaging one hour and a 

 half Fresh portions of water were added from time to time to keep 

 the volume nearly constant. After cooling, the contents of the flask or 



* T first used tubes constructed as above in 1881, but tried then paper pulp audfilms 

 of filter-paper on the linen. I first used asbestos in the summer of 1883, and found 

 it far superior to anythiug else. 



