H0*=9 . 



NO*=22 . 

 N*0*=15. 

 NO ^=38 . 

 N*0=23 . 

 N0 2 *=54 . 



C*0W4 . 

 C*0=22 . 



S*0=32 . 

 S^O^=40 

 As0 3 =198. 

 As*H 1 *=39 



Mr. J. J. Waterston on Chemical Notation, 521 



NC=26 . . Cyanogen. 

 N*C|H*=13£ Hydrocyanic acid. 

 N C 2 C1*=31. Chloride of cyanogen. 



Water. 



Protoxide of nitrogen. 

 Nitric oxide. 

 Hyponitrous acid. 

 Nitrous acid. 

 Nitric acid (dry). 



Carbonic oxide. 

 Carbonic acid. 



S*H=17 . 

 N^H^=81 



H*C1*=18£ 

 H*Br*=40£ 

 H^=63i 



Hydrochloric acid. 

 Hydrobromic acid. 

 Hydriodic acid. 



As^Cl 1 ^=92 . Sesquichloride of arsenic. 

 As 4 Br ^=158. Sesquibromide of arsenic, 

 As4l 1 2 = 225 . Periodide of arsenic. 



S*C1=52 

 Sfci=68 



Chloride of sulphur. 

 Dichloride of sulphur. 



Sulphurous acid. 



Sulphuric acid (dry). 



Arsenious acid. 



Arseniuretted hydrogen 



Sulphuretted hydrogen. 



Phosphoretted hydrogen 



Ammonia. 



Note.— In this last, though the vapour-density of Fl and of 

 Bo are both unknown directly, they become so indirectly by the 

 measured vapour-density of the compound. 



Bo^Ci 1 *=59i Terchloride of boron. 

 Bo^Fl^=33 . Fluoride of boron. 



N*C"Br*=53. Bromide of cyanogen 

 FeCl 3 = 1 64 . Sesquichloride of iron 



A1C1 3 =135 . Chloride of aluminium. 

 AlBr 3 =267 . Bromide of aluminium. 

 A1I 3 =408 . Iodide of aluminium. 



Note. — The values of Fe and Al here become known, though 

 the vapours of iron and aluminium cannot be weighed. The 

 specific heat seems a sure guide to molecular weights of metals. 



C*H 2 =8 

 CH 2 =14 



C 2 H 4 =28 

 C 3 H 3 =39 

 C 3 H 5 =41 



C*H 8 =68 



Organic Compounds. 



. Marsh-gas. 

 . Olefiant gas, 

 . Etherine. 

 . Benzin. 

 . Naphtha. 

 Turpentine, 



CH 2 . HO*=23 . . Alcohol. 

 2(CH 2 ) . HO*=37 . S. ether. 

 C%.HO^=16 . Pyroxylic spirit. 

 2(C^H).HO^=23. Pyroxylic ether. 



Note.— Alcohol cannot be expressed by CH 3 . 0', because one 

 H is in a burnt condition, and the only constituent it has to have 

 burnt with is 0^. 



Pyroxylic spirit cannot be expressed by C^H 2 .0* for the same 

 reason. The ethers also for the same reason. 



CH 2 0* = 22 . . . Aldehyde. 



Note. — The formula might require to be modified to CH . HO^, 

 Phil. Mag. S. 4. No. 1 78. Suppl. Vol. 26. 2 M 



