ETHYL, ALCOHOL FROM WOOD WASTE. 45 



From these figures it will be seen that all the material was equally 

 cooked and gave practically the same yields, irrespective of size 

 within the limits used. In addition, the material leached readily 

 without formation of fine stuff, and 88.4 per cent of the sugar present 

 was extracted without difficulty in three leachings. A certain 

 amount of sawdust or material of similar size, therefore, seems 

 necessary in order to obtain a good extraction, even though chips as 

 large as five-eighths of an inch with the grain may be cooked under 

 the conditions outlined in as short a time as 15 minutes and with 

 good yields. 



It has been observed in commercial practice that a mixture of dust 

 and chips in the proportion of 10 to 15 per cent of dust and 90 to 

 85 per cent of chips gives the best results in the diffusion battery. 

 If all dust or too much dust is used, the cooked material packs in 

 the cells, high pressures are required to force the extracting water 

 through it, and the material hangs in the cells at the time of dis- 

 charge, causing loss of time in operation. If dust-free chips are used, 

 the opposite is true; the extracting water percolates too fast, and 

 extraction is not good. With the proper combination of dust and 

 shredded chips, a 92 per cent extraction of the total sugar may be 

 obtained. 



LEACHING EXPERIMENTS. 



The determination of the number of cells in a diffusion battery 

 necessary to get a maximum extraction in a minimum time, with a 

 minimum amount of water, is a very important point in this process. 

 Furthermore, it was desirable to determine whether there was any 

 selective solubility between the different sugars present or the soluble 

 solids other than sugars. With this end in view, two series of cooks 

 were made under the same conditions, viz, 125 per cent of water, 

 2.5 per cent of sulphuric acid, a pressure of 7.5 atmospheres, and a 

 cooking period of 15 minutes. It is regrettable that an accident to 

 some of the condensing apparatus prevented blowing off these cooks, 

 and after each cook it was necessary to allow the digester to cool 

 gradually to 212° F. or less before the contents were discharged. 

 Undoubtedly reducing substances were formed and retained which 

 were the cause of erratic sugar data being obtained. 



Cooks Nos. 51 and 52 were preliminary and were made for the 

 purpose of outlining a method of procedure. The digested sawdust 

 from both cooks was put into the leaching tanks and successively 

 leached by sprinkling small quantities of boiling water over the 

 digested sawdust and collecting the drip as soon as it had drained 

 through the sawdust. The different extracts were then analyzed, 

 neutralized, and fermented in the usual manner with the following 

 results. 



