220 Prof. Graham's Note on the Constitution of Salts, 



Jead is basic in these compounds, but superadded to the orcine 

 like constitutional water ; a distinction which is well expressed 

 in their formulae, by placing the symbols for water and oxide 

 of lead after and not before that of orcine, or in the proper 

 place for water of crystallization in the formula of a salt. 



Potash, soda, oxide of silver, and oxide of ammonium, on 

 the other hand, are never found in this relation to a salt, or 

 discharging any other function than that of base to an acid. 

 Hence there are no such compounds as subsalts of these bases. 



In Peligot's late admirable paper on the varieties of sugar, 

 [Annales de Chimie, &c., t. 67. p. 113 *), he has formed the 

 compounds of that principle with barytes, lime, oxide of lead, 

 and common salt, and determined their composition with great 

 accuracy. Like preceding chemists he considers these com- 

 pounds as salts, in which sugar is the acid and the metallic 

 oxide the base, and continues to speak of them as saccharates, 

 although with an evident reserve. But the conclusion is b}' 

 no means necessary that sugar is an acid, and that the lime, 

 oxide of lead, &c. are basic to it. On the contrary, sugar 

 being a body neutral to test paper, is more likely to be a salt 

 than an acid. That the metallic oxide attached to it discharges 

 the function of the superadded water of crystallization of 

 so many bodies, appears to me evident from the following cir- 

 cumstances. 



1. It is separated from the sugar by the weakest acids, even 

 by carbonic acid. 



2. It replaces water in the sugar, which water can also be 

 replaced in part by an equivalent proportion of chloride of 

 sodium, or by the hydrates of barytes and lime. Now basic 

 water is never replaced by a salt, although constitutional water 

 frequently is. 



3. But the circumstance which is decisive of the lime and 

 oxide of lead not being basic in the sugar compounds is, that 

 analogous compounds do not exist, containing potash or any 

 of the strong alkaline bases of its class. No acid is known 

 which forms a salt with lime or lead, that does not also form 

 a salt with potash or soda ; but these last, as has been stated, 

 are never present in any other capacity than that of bases, and 

 are thus disqualified from replacing the water or magnesian 

 oxide in combination with sugar. 



The test of the non-hasic character of laater or a metallic 

 oxide in a compou7id^ is the absefice of a parallel combination 

 containing an oxide of the potash class. 



The fact that the combined water in sugar is strongly at- 

 tached and cannot be removed by heat, is no proof that the 



* A notice of M. Peligot's researches on this subject will be found in the 

 present Number, p. 237.-'Edit. 



