1824.] Rev. J. Topham's Epitome of Chemistry. 61 



weight of oxygen, but the weight of the atoms depends upon 

 that of the standard assumed : thus the weight of an atom of 

 hydrogen being 1, that of oxygen is 8, and phosphorus 12, but 

 an atom of hydrogen being 0-125, oxygen is 1, and phosphorus 

 1;5. 



" When combination takes place between two bodies in 

 various proportions, the numbers indicating the greater are exact 

 simple multiples of that denoting the least. Thus 100 parts of 

 carbon unite with 132^-, or 265 parts of oxygen, and no other. 

 Again, 100 parts of sulphur unite with 50, or 100, or 150 parts of 

 oxygen ; and in the intermediate ones no combination ensues." 



Now it happens that the greatest proportion is sometimes not 

 a multiple, but one-half more than the least ; this occurs with 

 respect to iron, of which 28 parts unite with 8 of oxygen to form 

 protoxide, and with 12 to form the peroxide. Again, the exact 

 quantity of oxygen with which 100 of carbon unite are 133 to 

 form oxide of carbon and 266 to form carbonic acid, but there 

 is an intermediate compound, namely, oxalic acid, composed ot 

 100 carbon and 200 oxygen. Once more ; 100 of sulphur unite 

 with 125 of oxygen to form hyposulphuric acid, as well as with 

 the three proportions above stated. 



In p. 12 we have a marvellously easy method of making sul- 

 phuric acid ; sulphur " by combustion in atmospheric air over 

 water, unites with oxygen, and forms sulphuric acid." How 

 foolish then have our manufacturers been in using nitre at a vast 

 expense ! We must, however, I believe, for sulphuric read sul- 

 phurous. 



Iodine appears also to have undergone a wonderful change of 

 properties ; according to Mr. Topham, it " is abundantly ab- 

 sorbed by water ; " the fact is, that water absorbs about 

 l-7000th of its weight. 



In the chapter on the alkalies, potash, soda, and ammonia 

 are mentioned ; and after incorrectly stating that the last 

 " next to hydrogen gas, is the lightest known ponderable body," 

 we are informed, that " the other alkalies are lithina, delphine, 

 brucine, vauqueline," and then we are instructed that "the bases 

 of the other alkalies [meaning the four last named], except 

 vauqueline (which is of vegetable origin) have also been formed 

 into amalgams with mercury, and are found to be metallic." 

 From this' we might conclude that delphia and brucia are not of 

 vegetable origin, and that the seeds of stavesacre, and the bark 

 of the brucia antidysenterica have been " found to be metallic." 

 The sentence which we have last quoted is followed by "oxygen, 

 therefore, in one proportion is the cause of alkalinity ; in another 

 (as will be seen) of oxidation ; and in a third of acidity." It is 

 difficult to conceive how so much error could have been crammed 

 into so small a space. If these statements were true, then we may 

 take any substance which is capable of uniting with oxygen; let it 

 be hydrogen, sulphur, or potassium, and by combining them in 



