1 6 ANIMAL CHEMISTRY LECTURE I. 



4 British Pharmacopoeia,' HgCl,* is indisputably wrong. In the 

 present state of knowledge, the matter no longer admits of any 

 question whatever. 



(15.) Having thus considered our primary hydrides of chlorine, 

 oxygen, and nitrogen, as typical of monad, dyad, and triad com- 

 binations in general, I now wish to direct your attention, lastly, 

 to their mutual relationship. Here we have them written up in 

 a convenient form : 



Chlorides Hydrates Amides 



HC1 H(HO) H(H 3 N) 



KC1 K(HO) K(H 2 N) 



ZnCl, Zn(HO), Zn(EL,N) 2 



PC1 3 P(HO) 3 P(H Z N) 3 



If under suitable conditions we act upon hydrochloric acid 

 HC1, water H.HO, and ammonia H.H 2 N, by a metal say by 

 potassium we obtain in each instance the same reaction. The 

 one atom of potassium turns out one atom of hydrogen; and 

 from each of the three molecules, instead of chloride, oxide, and 

 nitride of hydrogen, we get the chloride, hydrate, and amide of 

 potassium, which may be regarded as compounds of potassium K, 

 with the residues or radicles chlorine Cl, eurhyzen HO, and 

 amidogen H 2 N. Hence, caustic potash and potassamide may be 

 regarded as the hydrated and ammoniated forms of chloride of po- 

 tassium ; and in a similar manner, to nearly every chloride, mineral 

 or organic, simple or compound, there exists a corresponding 

 hydrate and amide bearing to it the same relation that caustic 

 potash and potassamide respectively bear to chloride of potassium. 

 If we consider chloride of potassium, for instance, as a com- 

 pound of metallic potassium, with the residue from hydrochloric 



* Hg; atomic weight, 200; atomic heat, 6-38: Hg ; atomic weight, 

 100 ; atomic heat, 3-19, or half that of the other elements. So that in un- 

 dergoing an equal increment or decrement of temperature, 200 parts of 

 mercury absorb or evolve the same, and 100 parts of mercury only half the 

 amount of heat absorbed or evolved by 23 parts of sodium, 65 parts of zinc, 

 108 parts of silver, 210 parts of bismuth, &c. 



