174 ANNUAL OF SCIENTIFIC DISCOVERY. 



to boil, after which twenty-two pounds of chalk are added to neutralize 

 the free acid ; but this must be put in very slowly, on account of the 

 violent evolution of the carbonic acid set free by the new combina- 

 tion, which produces sulphate of lime. The liquor is then strained 

 through coarsely pulverised bones spread on straining-cloths. The 

 filtered liquor is gradually brought into flat pans and evaporated till 

 it is reduced to half its volume, when it is a second time boiled, with 

 charcoal and bullock's blood, and then refined and filtered. One hun- 

 dred parts of dry starch yield about one hundred parts of sugar, 

 which is obtained 'by concentrating the syrup and putting it into casks, 

 where it is left to cool. After two days crystallized sugar is found in 

 the casks, with some liquid, which is drawn off. Thus by the aid of 

 chemistry we obtain sugar from potato-starch, sulphuric acid, chalk, 

 and water. This sugar is used for giving more " body " to the Bur- 

 gundy wines, and for confectionery. It is known chemically as 

 grape-sugar. 



PRODUCTION OF SUGAR IN THE URINE BY WOUNDING THE BRAIN. 



AN important and entirely unexpected discovery made recently by 

 M. Bernard has been announced to the French Academy. He has 

 found that by wounding a certain part of the floor of the fourth ven- 

 tricle, the composition of the urine becomes altered, and sugar makes 

 its appearance in it. The puncture is made by passing the instru- 

 ment through the inferior orifice of the ventricle, and soon afterwards 

 the urine of the animal (a rabbit), which before the operation is turbid, 

 alkaline, and free from saccharine matter, becomes abundant, clear, 

 and contains in solution a very large quantity of sugar, and resem- 

 bles that of a diabetes. In general not more than an hour and a half 

 or two hours are requisite for the complete production of this change 

 in the characters of the urine. The blood also contains a large 

 amount of sugar. The experiments have hitherto been made upon 

 sixteen rabbits; and by varying them, M. Bernard has found that the 

 point of the fourth ventricle which must be wounded to produce this 

 remarkable phenomenon of the appearance of sugar in the blood and 

 urine is very limited, and corresponds to a space situated a little above 

 the origin of the eighth pair of nerves. These results, which are so 

 surprising from their novelty, cannot at present be in any way ex- 

 plained. They merely serve to show the remarkable influence which 

 the nervous system exerts upon the functions of nutrition ; and in this 

 light they deserve the serious attention of chemists. 



ON THE ORIGIN OF SUGAR IN THE ANIMAL ECONOMY. 



IT has been generally maintained that sugar exists in the blood of 

 animals only when they have previously eaten substances containing 

 it, or capable of being converted into it, the economy having, in 

 fact, been most explicitly denied the power of making sugar, its sole 

 province being that of destroying it and causing its disappearance. 

 As sugar is found in the blood after the digestion of amylaceous and 

 saccharine substances, it has been hastily assumed that its existence is 



