Antiseptic Action and Chemical Constitution. 



333 



1 : 100000 and upwards, in 24 series, 1 : 40000 in 2 series, and 1 : 40000 failed 

 to sterilise in 1 series. With Staphylococcus aureus, however, the range 

 of variation was distinctly less. Accordingly, the numerical values recorded 

 here must be interpreted in the light of the above results (5). It should be 

 noted, however, that in comparing certain closely related compounds in which 

 marked alterations in antiseptic power may be produced by relatively slight 

 chemical differences, e.g., the methochloride and the hydrochloride of the same 

 base, the two substances have been tested on the same occasion and with the 

 same specimen of medium and culture, thereby reducing as far as possible 

 the action of uncontrollable factors. 



Fragments of the Acridine Molecule. 



Table I includes all the compounds tested, and comprises pyridine and 

 quinoline derivatives and dinaphthylimine. The striking feature, in general, 

 is the low grade of antiseptic power shown by these bodies. Thus, the 

 hydrochlorides of quinoline [3], tetrahydroquinoline [15], and the amino- 

 quinolines (o [4], m [6], p [8], and a [10] ), all failed to sterilise in dilutions 

 exceeding 1 : 2000 either in peptone water or in serum. The methochlorides 

 of the aminoquinolines [7, 9, 11], except in the case of the ortho-compound [5], 

 showed accentuation of antiseptic action in serum, as compared with the 

 hydrochlorides of the corresponding bases, a characteristic result which will 

 be discussed in more detail when dealing with the acridine group. The 

 hydrochlorides of a- [17] and /3-naphthoquinoline [19] were slightly more 

 active.* No striking difference could be established between these and their 

 tetrahydro-derivatives [22, 23]. Diamino /3-naphthoquinoline [24] also 

 showed no enhanced efficiency. The methochlorides (or methosulphates) of 

 both naphthoquinolines [18, 20, 21] and of diamino-/3-naphthoquinoline [25] 

 showed intensified action in serum. The 8-hydroxyquinoline sulphate [12], 

 long known as an antiseptic under the name of " chinosol," is included for 

 comparison ; its activity for Staphylococcus aureus contrasts with the slight 

 effect of hydroxyacridine compounds [67] and of the aminoquinoline com- 

 pounds as antiseptics, but it is very weakly antiseptic for B. coli. On the 

 other hand, it is remarkable that the methochloride [13] and methopicrate [14] 

 of the base do not show enhanced action. l-l'dinaphthyl-2-2-imine [28] 

 exhibits great discrepancy between its powerful action on. staphylococcus and 

 lack of effect on B. coli, which is similar to that exhibited by the triamino- 

 tviphenylmethane compounds, hexa-methyl and ethyl-violet. But the most 

 striking character of this substance is the reduction in action produced by 



* Previous results recorded for a- and /3-naphthoquinoline were obtained with less pure 

 preparations (see 'Journal of Pathology and Bacteriology,' vol. 24, p. 127 (1921)). 



