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Notices respecting New Books, SSI 



of the same carbonat be exposed for a short time to a red heat, 

 and afterwards let the gas be expelled from it in the same appa- 

 ratus, and it will be found to occupy exactly the same space as 

 that obtained from the two grains of crystallized salt in the 

 former experiment. 



" The same results are obtained from the super-carbonat and 

 the sub-carbonat of soda. 



^^ Super-sulphat of potash, in like manner, contains twice the 

 quantity of acid as the neutral sulphat. Let twenty grains of 

 carbonat of potash be mixed with about twenty-five grains of 

 sulphuric acid in a covered platina crucible, or in a glass tube, 

 atid this mixture gradually heated till it ceases to boil, and be- 

 comes slightly red-hot. This will produce the super-sulphat of 

 potash, which will be very nearly neutralized by an addition of 

 20 grains of the same carbonat of potash. 



" The common super-oxalat of potash is shown by Dr, Thom- 

 son to consist of potash united to twice the quantity of oxalic 

 acid necessary to saturate it. If two equal portions of this su- 

 per-oxalat be taken, and one portion calcined, so as to destroy 

 the acid, the alkali that remains will be just sufficient to saturate 

 the other portion. 



" When nitric or muriatic acid is added to the common super- 

 oxalat of potash, the latter salt is only partially decomposed, and 

 crystals form in the mixture, which are found on examination to 

 be a Quadroxalat of Potash, or potash wMhfour times as much 

 acid as will saturate it. 



" The formation of these various salts vvith a definite excess 

 of acid, which is expressed by a simple multiple of the least de- 

 finite quantitv, is ])articularly important, as it affords an answer 

 to the powerful objection urged by M. BerthoUet against the 

 common opinion of chemical affinity. This eminent chemist 

 shows that a considerable excess of a weaker acid will decom- 

 pose a com])ound of a base and a stronger acid ; for example, 

 that a large quantity of nitric acid added to sulphat of potash 

 will occasion some crystals of nitre to form, though the nitric 

 acid has a weaker affinity to potash than the sulphuric. But 

 though there is an undoubted decomposition of some portion of 

 the sulphat of potash in this case, it is highly probable that for 

 every particle of nitre formed there is an equivalent quantity of 

 a super-sulphat of potash produced, in equally definite propor- 

 tions with the neutral sulphat, and in which, probablv, the acid 

 is in the ratio of a simple multiple of that which exists in the 

 neutral salt. 



*' Among the philosophers who within these last few years 

 have laboured with the greatest zeal and success in discovering 

 the laws of chemical affinity, a distinguished place is due to Pro- 

 fessor 



