18 



The dilute alcohol vapor is condensed in the cooler (7, and flows 

 through the tail pipe K to the closed receiving tank J/, which is fur- 

 nished with a vacuum gauge F, and an outlet to the vacuum pump 0. 



The excess of alcohol, after the tank M is filled to the dotted line, is 

 removed through the system of pipes indicated by a pump and sent 

 directly to the condensing still or to a tank arranged to feed that still. 

 The vacuum pump should be operated only sufficiently to secure the 

 necessary vacuum in starting the apparatus and to remove any air 

 which may find entrance. 



The tail pipe K should be long enough to maintain a proper vacuum. 

 It can be made of equal length with the tail pipe P, which, being ar- 

 ranged to receive a heavier liquid, will discharge into the tank A. 



After leaving the still the sirup is pumped, as has been stated, to the 

 vacuum pan. This purified sirup boils as freely as the cane sirup of the 

 Louisiana plantations. In practice, owing to the small size of the vac- 

 uum pan, it was found advisable to introduce a few pounds of sugar 

 into the pan for use in building up the grain. The sirup was concen- 

 trated to proof and 50 pounds of fine-grained sugar added. This plan 

 was adopted in order to obtain grain comparable in size with that from 

 sirup boiled in large pans. Owing to the small size of the pan and the 

 free boiling of the sirup the entrainment was considerable, and on the 

 small scale on which the experiments were conducted the percentage of 

 loss was large. With the present pan arrangement this loss was una- 

 voidable, and introduces an element of error which would not obtain in 

 regular manufacture. Sirups not previously treated with alcohol boiled 

 heavily and with little loss from entrainment. 



It was quite noticeable that massecuites grained in the pan, from 

 sirups produced by the ordinary process, were difficult to purge, even 

 when left in the hot room a few days. Massecuites from sirup purified 

 by the alcohol process were boiled to a very high proof and were cen- 

 trifugaled immediately after leaving the vacuum pan. The ease with 

 which the centrifugal work was accomplished is of great importance, 

 since it enabled the rapid drying of the sugar and the manufacture of a 

 product of good polarization without the use of a wash. 



DIFFICULTIES ENCOUNTERED. 



It is unfortunate that experiments of as great importance as those 

 under consideration must necessarily be made with new machinery. 

 Under these conditions vexatious delays are unavoidable, no matter 

 how carefully the plans may have been carried out. In the present case 

 the experience of the Department and the nature of the experiment 

 rendered a new building and machinery on a small scale a necessity. 

 The work was pushed rapidly from the time of receiving the appropri- 

 ation, but much was left for the last few weeks, and as a result there 

 were many evidences of hasty and careless work. A great source of 

 vexation was the failure of certain pumps. The losses of time and sirup 



