340 Mr. C. H. Browning and others. Relationships between 



triaminotriphenylmethane dyes (2). The substitution of one hydrogen atom in 

 each of the amino groups by acetyl radicals practically abolishes the anti- 

 septic action, e.g., the sterilising concentration of 2.7. diaminoacridine chloro- 

 acetate [44] for Staphylococcus aureus in peptone water was 1 : 100000 and in 

 serum 1 : 200000, and for B. coli in peptone water 1 : 20000, and in serum 

 1 : 400000 ; on the other hand, with the diacetyl derivative [64] a concentra- 

 tion of 1 : 2000 failed in each case to sterilise. 



The carboxylic esters of 2.7. diamino-9.phenylacridine [65] and of 2.7. tetra- 

 methyldiamino-9.phenylacridine [66] were so weak as to suggest a marked 

 depressing effect of the carboxyl group on the antiseptic property. 



The replacement of the amino groups by hydroxyls also led to practical 

 abolition of antiseptic power, as is shown in the case of 2.7.dihydroxy- 



3.6. dimethylacridine, of which both the sodium salt [67] and the metho- 

 chloride [68] were tested. 



Comparative Efficiency for Staphylococcus aureus and B. coli. — Antiseptic 

 potency for Staphylococcus aureus and B. coli does not invariably run parallel ; 

 thus the lethal concentration in serum for staphylococcus is 1 : 100000, or 

 lower in the case of 2.7.diaminoacridine hydrochloride (or sulphate)' [35] and 

 methochloride [36], and other analogous derivatives [37-46], 2.7.tetramethyl- 

 diaminoacridine hydrochloride [52], methochloride [53] and methonitrate [54], 



2.7. diamino- 3.6.dimethyl acridine hydrochloride [48], and methochloride [49], 

 2.7.tetraethyldiaminoacridine methochloride [56] and methonitrate [57]. 

 2.7.diamino 3.6.dimethyl-9.phenylacridine methochloride [51], 2.amino- 

 3.methylnaphthacridine methochloride [59]. But in the case of B. coli only 

 the hydrochloride, methochloride, and analogous derivatives of diamino- 

 acridine [35-46] and of diaminodimethylacridine [48, 49], and the metho- 

 chloride of 2.amino-3. methyl naphthacridine [59] reach this level of 

 effectiveness. 



Phenazine Series. 



The striking feature of this series (see Table III) is the relatively poor 

 antiseptic power exhibited by the amino compounds in serum, especially for 

 B. coli. The only compounds exactly comparable with the acridine series are 

 those of the phenazine base [69, 70], 2.7.tetramethyl diaminophenazine 

 [80, 81], and 2.7.diamino-3.6.dimethylphenazine [86]. The enhanced effect of 

 the metho-compounds as compared with the hydrochlorides of the same base 

 is evident in the phenazine series ; but is not so striking as with certain of the 

 diaminoacridine derivatives. 



The relatively greater efficiency of the methochloride of 2.dimethyl- 

 amino-7.amino-6.methylphenazine [84], as compared with 2.dimethylamino- 

 7.aminophenazine [76], and of 2.7.diamino-3.6.dimethylphenazine [86] as 



