18 CHEMICAL AGENTS AXD PROTOPLASM [Cn. ] 



NH-CH N.CH 3 -CH 



I II I II 



CO C - KH CO C - N . CH 3 



I I ^>CO I I \CO 



NH-C=N X NH C = N ' 



xanthin. theobromine. 



N.CH 3 -CH 

 I II 



CO C-N.CH, 



I I ^CO 



N . CH 3 - C = N ' 



coffein. 



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



H 

 I 



HV /Cv /a 

 \c/ \c/ 



While benzol \ \ is rather inactive, 8 grammes 



/C\ /Gv 

 H/ \C/ ^H 



I 



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/ \0-OH HO-C/ \C-OH 



II II II 



HC \ /CH HC >. 



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. Algae die in a 1% solution after 20 to 30 



