100 Dr. Prout on the 'ultimate Composition 



moisture that usually adheres to it by exposure for some time 

 to a temperature of 212°, was found to be composed of 



Carbon 4-2*85 



Water 57*15 



Now, all the finest and purest specimens of loaf sugar of 

 commerce that I have yet examined, give, when similarly 

 treated, precisely the same results. They may therefore be 

 considered as identical in their composition with sugar candy*. 

 Cane sugar appears to undergo no change whatever at the 

 temperature of boiling water ; but at about 300° it begins to 

 melt, and assume the form of a dark-brown liquid. In one 

 experiment, after exposure to this temperature for seven hours, 

 it lost *6 per cent, only of its weight, but its properties seem 

 to have been permanently injured. Berzelius however has 

 shown that, on being combined with lead, sugar parts with 

 about 5*3 per cent, of water without undergoing decomposi- 

 tion ; for he has likewise shown that it may be obtained again 

 from the lead in its original state. This saccharate of lead I 

 have several times formed, and once by accident I obtained it 

 iu the state of beautiful crystals. 



Sugar of Honey. — The lowestf well-defined sugar that I 

 have yet examined, was first obtained from Narbonne honey, 

 by means of a process formerly pointed out by me for obtain- 

 ing diabetic sugar in a state of purity J. This, deprived of 

 its hygrometric moisture by being placed under a receiver 

 with sulphuric acid for several days, was found to consist of 



Carbon 36*36 



Water 63*63 



This sugar in the ordinary state of the atmosphere usually 

 contains more water than indicated by this analysis ; that is 

 to say, generally about 64*7 per cent. On the other hand, 

 on exposure to a temperature considerably below that of boil- 

 ing water, it rapidly loses about 3 per cent, of water, and be- 

 gins to assume the fluid form : kept at the temperature of 

 boiling water for 30 hours, it lost in one experiment upwards 



* Dr. Ure states that he has found sugar to contain upwards of 43 per 

 cent, of carbon ; but no such specimen has occurred to me, though 1 by 

 no means deny its existence. Indeed I have hitherto met with no sugar 

 as it occurs in commerce, yielding more than 42*5 per cent, of carbon, and 

 frequently it contains considerably less than this. 



f In commerce, these imperfect sugars are denominated weak or low 

 sugars, which last epithet is here employed in this sense. 



J Med. Chirurg. Trans, viii. 537. I have little doubt that honey con- 

 tains a still lower sugar, and which is incapable in this country (at least 

 during a great part of the year), of assuming the solid form. This is pro- 

 bably the liquid sugar of Proust. 



of 



