18 CHEMICAL AGENTS AND PROTOPLASM [Cn. ] 



NH-CH N.CH 3 -CH 



I II I II 



CO C-NH CO C-N.CH 3 



I I \CO I I \ CO 



NH-C-N NH C = N ' 



xanthin. theobromine. 



CO C - N . CH 



N . CH 3 - C = N ' 



coffein. 



are successively less poisonous. (LoEW, '93, p. 46.) 



H 

 I 



H \c/ C \c/ H 



While benzol \ is rather inactive, 8 grammes 



H/ '\0/ \H 



H 



per day being withstood by the human organism, with the 



replacement of the H atoms by OH the substance becomes 

 more poisonous in direct proportion to the number of H 

 atoms thus replaced. (LoEW, '87, p. 440.) Thus there fol- 

 low in order of poisonousness : 



H H H 



I I I 



HC/ \C-OH HC/ \C-OH HO-C/ '\C-OH 



CH HC V /CH HC V /CH 



\oX \c/ 



I I I 



H OH OH 



phenol (monoxybenzole). resorcin (dioxybenzole). phloroglucin (trioxybenzole). 



Phenol (or carbolic acid) and its derivatives attack unstable 

 substances, especially aldehydes, forming insoluble products. 



Phenol itself produces in the higher animals a paralysis of 

 the nerve centres. Algse die in a 1% solution after 20 to 30 



