52 On the Cause of Chemical Pioportions, [Jan. 



the class of metLils, I sliall distinguish tliose that have the same 

 initials with atiothcr metal, or a metalloid, by writing the first two 

 letters of the word. :■!. If the first two letters be common to two 

 metals, I shall, in that case, add to the initial letter the first 

 consonant which they have not in common : for examj»le, S = 

 sulphur, Si = silicium, St = stibium (antimony), Sn = stannum 

 (tin), C = carbonlcum, Co = cobaitum (cobalt), Cu = cuprum 

 (copper), O = oxygen, Os = osmium, &c. 



The chemical sign expresses always one volume of tlic substance. 

 When it is necessary to indicate several volumes, it is done by 

 adding the number of volumes: for example, the oxidiim cuprosum 

 (j^rotoxide of copper) is composed of a volume of oxygen and a 

 volume of metal ; tberefore its sign is Cu + O. The oxidtnn 

 cupricuin (peroxide of cojvper) is composed of 1 volume of metal 

 and 2 volumes of oxygen; therefore its sign is Cu + 2 O. In 

 like manner, the sign for sulphuric acid is S 4- i^ O; for carbonic 

 acid, C + 2 O; for water, 2 H + O, ike. 



When v.e express a compound volume of the first order, we 

 throw away the +, and place the number of volumes above the 



3 2 



letter : for example, Cu O + S O = sulphate of copper, Cu O + 



2 S (3 = persulphate of copper. These formulas have this advan- 

 tage, that if we take away the oxygen wc see at once the ratio 

 between the combustible radicles. As to the volumes of the second 

 order, it is but rarely of any advantage to express them by formulas 

 as one volume ; but if we wish to express them in that way, we 

 may do it by using the parenthesis, as is done in algebraic formulas: 

 for example, alum is composed of 3 volumes of sulphate of alumina 



and 1 volume of sulphate of potash. Its symbol is 3 (Al O + 



3 » 3 ... 



2 S O) + (Po 4- 2 S O). As to the organic volumes, it is at present 

 very uncertain how far figures can be successfully employed to 

 express their composition. We shall have occasion only in the 

 following pages to express the volume of ammonia. It is G H + 



N + O, or H K O. 



IV. UVighi of elemenlarif J'olumes compared uulh thai of Oxygcri 



Gas. 



A. — Oxygen. 

 The volume of oxygen' is expressed by the letter O. It is consi- 

 dered = 100. 



B —The Metalloids. 



1. Sulphuricmn, sulphur fS). — I have already mentioned that we 

 may determine the volume of this body by the quantity of sulphur 

 which combines with a given weight of metal compared with the 

 oxvgcn which wnibines with the same metal. It is to be supposed 

 thiit the relative quantities of sulphur and oxygen have the same 



