462 Analyses of Books, [Dec. 



modern work of the " pure chemists." It might be supposed 

 that the word teny was accidentally substituted for o;/e, of water; 

 but the symbols agreeing with the former, we must admit 

 what we find so often repeated, to express the state of the 

 author's knowledge on the subject, and it is astonishing that it 

 should be so erroneous. 



In p. 177, Mr. Gray states, that from " the quantity of 

 ammonia required for saturating acids, it may in consequence of 

 this law be inferred that ammonia contains about 46 per 

 cent, of oxygen ; and its change into azotic gas and hy- 

 drogen gas, by being passed through a red-hot tube, shows 

 that this is united with 36 of nitricum and 18 of hydrogen; 

 so that the composition of ammonia is 6 H + N -f O." 

 If there be any thing in chemical science which appears 

 to be settled, it is, that ammonia contains no oxygen ; 

 and the view which Mr. Gray has given of its composition is 

 calculated to puzzle much more than to inform. If the student 

 after reading this passage were to look into the chemical works 

 of Thomson, Henry, or Brande, he would find no mention either 

 of oxygen or nitricum existing in ammonia. These speculations 

 of Berzelius respecting the compound nature of azote, should 

 have found no place in an elementary work. 



The statements of the nature and atomic constitution of the 

 various salts are such as will give the pupil no idea of their 

 composition ; thus in p. 204, we are told that " acetic acid, 

 boiled on about one-quarter of its weight of litharge to three- 

 quarters its bulk, then set by to settle and poured oil' clear, 

 is the liquor plumbi acetatis of the Pharmacopceia, a dram of 

 which added to a pint of water, and a dram measure of proof 

 spirit, forms the well-known Goulard's lotion. These are solu- 

 tions of a salt which may be crystallized in plates, and is a sub- 

 tritacetate of lead, or acet. ac. + 3 ox. lead." 



The fact is, that this solution is a subbinacetate of lead, but 

 if it were what Mr. Gray represents it ta be, what idea of the 

 proportions of its constituents can the pupil acquire, without 

 knowing the weight of the atoms of acetic acid and oxide of 

 lead ? The composition of 100 parts ought to have been stated 

 in the usual way; added to this when treating of the nomencla- 

 ture of salts in p. 81, no rules are given for describing those 

 which contain an excess of base. On the same ground we 

 object to the following statement : " Moist iodine added to 

 phosphorus yields a sour colourless gas, which is rapidly 

 absorbed by water, and must be collected in a quicksilver appa- 

 ratus ; a gallon of this gas v/eighs about 311 grains. Here the 

 changes are either 1^ -h P into I- + P', or I + P + H' into 

 I H + P* ; and the new acid is called the iodic or hydroiodic." 

 The pupil would naturally suppose, that Mr. Gray considers the 

 iodic and hydroidic acids (properly hydriodic) as similar ; but he 

 ought to have known, that iodic acid consists of oxygen and 



