18 CHEMICAL AGENTS AND PROTOPLASM [Cn. J 



NH-CH N.CH 3 -CH 



I II I II 



CO C--NH CO C-N.CH 3 



NH - C == N NH C = N 



xanthin. theobromine. 



N.CHg-CH 



I II 



CO C - N . CH 3 



' I ^CO 



N . CH 3 - C = N / 



coffein. 



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



H 



I 



Hv /C\ /H 

 \C/ \C/ 



While benzol \ \ is rather inactive, 8 grammes 



r r 



/ \ / \ 



HX \C/ \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 



II II I I 



HC CH HC 'CH HC V /CH 



\/ 



H OH OH 



phenol (rnonoxybenzole). 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. Alga3 die in a 1% solution after 20 to 30 



