1815.] Elements of Organic Nature are' comUned. 261 



If we pour sugar into a solution of subacetate of lead, no pre- 

 cipitate takes place. But we should deceive ourselves, were we to 

 conclude from this, that sugar does not combine with oxide of lead, 

 or that it does not form an insoluble compound with that oxide. A 

 solution of sugar not only dissolves oxide of lead ; but by a long 

 digestion it combines with an excess of that oxide, and forms an 

 insoluble, light, white, and bulky compound. This compound 

 dissolves in acetate of lead, subacetate of lead is formed, and the 

 sugar is disengaged. I shall have occasion to speak more of this 

 combination below. If we pour some drops of caustic ammonia 

 into a solution of sugar of milk, we do not observe any change. 

 The ammonia acts as a re-agent, just as if the sugar of milk were 

 not present. We should deceive ourselves were we to conclude 

 from this that sugar of milk and ammonia have no affinity for each 

 other. We have only to macerate at the temperature of 122° a 

 solution of sugar of milk with oxide of lead, and then to drop a 

 little ammonia into the filtered liquid. This liquid, which is a 

 combination of sugar of milk and oxide of lead, is decomposed, 

 and an insoluble compound of sugar of milk with an excess of 

 oxide of lead is precipitated. This precipitation is owing to the 

 affinity of ammonia for sugar of milk, which it divides with the 

 oxide of lead. 



It is, in general, very difficult to obtain neutral combinations 

 with these substances; at least unless this can be done when they 

 are in solution in water, which has the same action on them as on 

 the metallic oxides placed round the point of indift'erence of the 

 electro-chemical chain ; as the oxide of bismuth, antimony, tel- 

 lurium, &c. We know that it is impossible to obtain a neutral 

 muriate of these oxides, by treating them with liquid muriatic 

 acid ; we obtain only an insoluble submuriate and a soluble muriate 

 with an enormous excess of acid. In the same manner when we 

 digest a solution of common sugar, or sugar of milk, with oxide of 

 lead, we obtain only an insoluble compound with an excess of 

 oxide of lead, and a soluble combination with an enormous excess 

 of sugar. If you pour ammonia into a solution of sugar, nothing 

 indicates that the substances combine, and the ammonia evaporates 

 from that solution as easily as from pure water. But if you expose 

 sugar in powder to the action of ammoniacal gas, the sugar absorbs 

 the gas, and forms with it a compound. Here the same thing 

 takes place as when you exix)sc oxide of antimony to the action of 

 muriatic acid gas. These observations, I conceive, not only prove 

 that the ternary vegetable oxides have a general tendency to com- 

 bine with salifiable bases ; but they point out also the reasons why 

 this general tendency has hitherto remained unnoticetU 



To be able to speak of these combinations it will be necessary to 

 pive them names, and 1 thought it would be agreeable to the prin- 

 ciples of the chemical nomenclature to name, for example, a com- 

 bination of sugar with oxide of lead, according to the different 

 degrees of saturation, iaccliaralCf sub-sacdiarale, super succliarate 



