CANE SUGAR. 



121 



and which remedied the "lurching" effects of the older method of 

 adjustment, was introduced. 



4. The addition to our equipment which gave the most satisfaction, 

 and which proved to be the most indispensable of all our instruments — 

 if comparisons are legitimate in a work whose success depends on the 

 perfection of every one of a multitude of conditions — was a Schimdt 

 and Hansen saccharimeter of the best construction. 



It is to be remembered in this connection that, in Series I, we had 

 no means of ascertaining what had occurred in the solutions while 

 in the cells except the test of Fehling and the examination of the 

 solvent in which the porous part of the cells was immersed; also that, 

 having found no solute in the latter, and but little invert sugar by the 

 former, we were obliged to conclude, from the evidence available, that 

 the solutions had maintained their concentration without much altera- 



Fig. 49. — Interior view of water compartment with covers partly removed, 

 (e) and (e') air tubes; (b) tube for circulating water. No devices for heating or cooling the water. 



tion of the solute. If this conclusion were correct, and it was believed 

 to be so in the main, the results of the measurements of Series I were 

 trustworthy and furnished strong experimental evidence in support 

 of the deductions of van't Hoff. 



It had been suspected, however, that the inversion occurring in the 

 cells was somewhat larger than it had been found to be by the method 

 of Fehling, and the object sought by the introduction of the polariscope 

 into the investigation was to measure this supposed greater inversion 

 by the more accurate optical method. The quantity of invert sugar 

 was to be measured by the loss in rotation, and one-half the pressure- 

 equivalent of the invert sugar so found was to be deducted from the 

 observed pressure, in order to arrive at the correct osmotic pressure of 

 the original solution of cane sugar. 



