THE CARBONATION PROCESSES 



287 



theoretical maximum of carbon dioxide being 38-7 per cent. ; in general 

 practice the percentage Ues between 25 and 30 per cent., with from i to 3 

 per cent, of oxygen and 65 to 70 per cent, of nitrogen. Traces of carbon 

 monoxide ma}' be present, but should not rise above i per cent. ; sulphur 

 dioxide derived from sulphur in the coal ma\' also occm\ 



Carbon Dioxide Pumps, — The pumps used to aspirate the carbon dioxide 

 are now shde-valve pumps similar in design and construction to those used 

 in the dry vacuum process described in the chapter on Evaporation. A table 

 of their capacities is given below, taken from a Continental maker's catalogue. 



Quantity of gas sucked per 



hour, cu.m. 

 Diameter of steam cylinder, 



mm. 

 Diameter of carbonic acid 



cj-linder, mm. 

 Piston stroke, mm. 

 Revolutions per minute 

 Steam inlet, mm. ... 

 Steam outlet, mm. 

 Diameter of suction pipe, 



mm. 

 Diameter of delivery pipe, 



mm. 



4050 



700 



1 100 

 1000 



45 

 170 



185 

 270 

 250 



Differences between Carbonation and Defecation. — In addition to the 



differences already noted, others, best obser\-ed in the follo^nng analj'ses of 

 molasses quoted from Geerhgs,*^ exist. They lie mainh- in the greater quan- 

 tity of lime salts, in the very small optical activity of the reducing sugars, 

 and in the smaller quantity of " gums." 



In the reports issued for the Mutual Control of Java factories for the 

 year 1912 the following averages can be deduced. Seventeen carbonation 

 factories raised the purity of the raw jmce from 82-2 to 84-9, or 2*7 units, 

 whereas 114 defecation factories raised the purity from 8o-i to 82-4, or 2-3 

 units. A difference so smaU as this is without significance, and especially 

 so since the purities referred to are on a polarization basis. 



The relative yields are stiU in the controversial stage in Java. One of 

 the latest estimates of these, referring solely to a production of white sugar, 

 is that of Van der Went.' Putting the ^deld with sulpho-defecation at 100, 

 he finds that with double carbonation is 100-32, with de Haan's method 

 100-64, 3^nd with Bach's process 100-96. Compared with the fields of 96° 

 test sugar, the results of de Haan in one and the same factory may be 



