AMIDATED COMPOUNDS. 17 



acid, we can in the same way consider caustic potash as a 

 compound of the metal with the residue from water, and potass- 

 amide as a compound of the metal with the residue from ammonia ; 

 and hereafter it will appear that some of the most complicated 

 products of tissue metamorphosis are but the ammoniated forms 

 of comparatively simple bodies, just as potassamide is the ammo- 

 niated form, and caustic potash the hydrated form, of chloride of 

 potassium. Again, if in chloride of zinc ZnCl 2 , we replace the 

 two atoms of chlorine by eurhyzen or peroxide of hydrogen, we 

 obtain hydrate of zinc ; whereas if we replace them by amidogen 

 we obtain zincamide, as also shown in the above table. Similarly 

 if in chloride of phosphorus PC1 3 , we replace the three atoms of 

 chlorine by peroxide of hydrogen, we obtain phosphorous acid ; 

 whereas if we replace them by amidogen we obtain phosphor- 

 amide; these three bodies being, so to speak, the phosphorus 

 representatives of hydrochloric acid, water, and ammonia, or of 

 chloride of potassium, caustic potash and potassamide. 



(16.) Passing on to organic compounds, marsh gas is found to 

 consist of one atom of carbon united with four atoms of hydrogen, 

 so as to constitute the fourth or tetrad term of our series of 

 typical hydrides. Now, if we take the chlorine derivative of 

 this marsh gas that is, if instead of CH 4 we take CH ? C1. an'1 

 replace the atom of chlorine by an atom of peroxide of hydrogen, 

 we obtain ordinary wood-spirit, whereas if we replace it by 

 amidogen, we obtain methylamine, a very common product of 

 the putrefactive decomposition of animal matter, as formulated in 

 the first line of the next table : 



Chlorides Hydrates Amides 



C H 3 C1 C H 3 (HO) C H 3 (H 2 N) 



C Cl a CO (HO), C (H a N\ 



C 3 N 3 C1 3 C 3 N 3 (HO) 3 C 3 N 3 (H,N) 3 



C a H 3 C10, C a H 3 (HO)O a C,H 3 (H 2 N)O a 



C a H 5 ClS0 3 C a H 5 (HO)S0 3 C a H 5 (H a N)S0 3 



Again, if in phosgene gas COC1 2 , we replace the two atoms of 

 chlorine by peroxide of hydrogen, we obtain carbonic acid ; 



c 



