350 



Dr. Ure on the Ultimate Analysis of 



[May, 



Table of Organic Analyses. 



" Remarks on the preceding Analyses." 



" The sugar which I employed," says Dr. Ure, " had been 

 purified by Mr. Howard's steam process, and was so well stove- 

 dried, that it lost no appreciable portion of its weight, when 

 enclosed along with sulphuric acid in vacuo. The diabetic sugar 

 has a manifest excess of oxygen, which, I believe, to be the case 

 with all weak sugars, as they are called by the sugar refiners. I 

 consider this excess of oxygen as the chief cause which coun- 

 teracts crystallization, and, therefore, the great obstacle to the 

 manufacturer. The smallest proportion of carbon, which I have 

 ever found in any cane sugar, was upwards of 41 per cent. The 

 experiments on starch and gum were among the earliest which I 

 made, and the results differ so much from those given by other 

 experimenters, that I shall repeat the analyses at the earliest 

 opportunity. The constituents of the above three bodies, refer- 

 red to the prime equivalent scale, will be approximately as 

 follows : * 



Sugar. Starch. 



Carbon 5 atoms .... 5 atoms 



Oxygen 4 .... 5 



Hydrogen ... 4 .... 4 



. . . . 



Gum. 



4 atoms 



5 



4 



" Starch is liable to a similar deterioration with sugar ; that 

 is, some species of it make a much firmer coagulum with hot 

 water than others ; a difference probably due to the proportion 

 of oxygen. The starch here employed was that of commerce, 

 and was not chemically desiccated : hence, the redundancy of 

 water beyond the equivalent proportion. A little hygrometric 

 moisture was present also in the gum, as it was not artificially 



" The following are the equivalent numbers employed by Dr. Ure in this paper :— 

 Oxygen, 1*0; hydrogen, 0-125 ; carbon, 0*75; azote, 1-75. 



