144 Afialyses of Books, [Aug^ 



1 Now the question wliich arises is this : — Can silica be sepa- 

 rated from the soda with which it has been fused by the 

 agency of water, and without the action of an acid? If the 

 fact be so, it is quite new to us ; but we cannot help thinking 

 that some part of the operation is omitted to be stated. 



The atomic weights of the fixed alkalies, alkaline earths, and 

 their metallic bases, are all given as in the author's System, so that 

 his experiments which merely confirm former statements call tor no 

 particular observations. Indeed with respect also to the metals 

 the greater number, and all the more miportant ones, agree 

 with those given in the System. There are, however, some 

 variations and important additions in these bodies ; such 

 are the atomic weights of palladium, iridium, titanium, tungsten, 

 and uranium, and of many compounds containing them. With 

 respect to uranium, it is a curious fact that it has a strong dis- 

 position to form sesquisalts; with these additions, we may 

 now consider the^iatottrife weights of the metals as settled, except 

 that of osmiun^r '(-o ^0 ^J"'0^ 



While adopting the* xjonvposition of th^; oxides of copper as 

 usually given, Dr.T.ha^, and, we think, without sufficient reason, 

 altered his opinion of their atomic constitution ; he now consi- 

 ders the black oxide as a compound of an atom of oxygen 1, and 

 one of copper 4; and the red oxide as a suboxide constituted 

 of two atoms of copper 8, and one atom of oxygen 1 . 



It is remarked by the way, that such suboxides a& that of copper 

 '* in general are incapable of constituting permanent salts with 

 acids." Now as far as we know, no such suboxides exist, the 

 only unquestionable one being the suboxide of silver formed by INI r. 

 Faraday, and which consists of three atoms of silver and two of 

 oxygen. It is indeed true that two suboxides of manganese 

 have been mentioned, but their existence is much too problema- 

 tical to serve as the basis of a general law ; one of them indeed 

 is stated to be incapable of combining wi^t^h acids,, and no proof 

 has, we beHeve, been offered that the other unites with them. 



When treating of the salts of copper, vol. i. p. 420, note. Dr. 

 Thomson says, " It was the consideration of the salts^ of copper 

 that induced me to adopt 4 for the atomic weight of copper; for 

 if we represent the atom of copper by S, all the salts of copper, 

 without exception, will be bi.^ults, or will contain 2,i\tf>pisof 

 acid united to 1 atom of oxide." This assertion appears to be 

 .of too sweeping a nature, unless the so/uhlc salts only oi, copper 

 be meant, and, ey,eA .then we question its accuracy. Amojig 

 those which would consist of one atom of each ol' its constitu- 

 ents ar© those. ;Which Dr. Tlmnison calls disalLs, tlu re aru' the 

 disulphate, dicad:)onal,e, verdi^ris^ and probably al^(j ihc msoln- 

 "ble muriate and nitrate. It, }io\v(;\t'r, the tact were .^o, that all 

 the salts of copper vvere insoluble except the bisalts, this cir- 

 cumstance does not apj>€at to be a sufiicient cause for making 

 60 glaring an exception to the general rule, that when ^two 



