TOXICOLOGY AND PHARMACOLOGY 403 



be drawn from the process of dyeing; common salt or sodium sul- 

 phate is frequently added in dyeing cotton in order to get a more 

 rapid and complete utilization of the bath. The simplest explana- 

 tion of this is that there has been diminution in the solubility of the 

 dye by means of the added salt (i.e., the dye is made more colloidal) 

 and as a result of this a stimulation of adsorption occurs. This idea 

 guided SPIRO and BRUNS * in their experiments. They found that 

 salts and other substances which did not "salt out" phenol from 

 aqueous solutions, such as sodium benzoate, urea, glycerin, etc., had 

 no effect in strengthening the disinfectant action of phenol. Pyro- 

 catechin may be precipitated by ammonium sulphate but not by 

 common salt; the former increases the disinfectant action of pyro- 

 catechin, while the latter does not. It is also interesting that 

 according to PAUL and KRONIG equimolecular quantities of salts 

 added to a 4 per cent carbolic solution increases its action in the fol- 

 lowing order: NaCl > KC1 > NaBr > Nal > NaN0 3 > C 2 H 3 ONa. 

 According to SPIRO and BRUNS,* the same order obtains for the 

 precipitating action of these salts on phenol; however, the sulphates 

 exert a much more powerful effect. The close relationship of this 

 series of salts to albumin precipitation and to many other biological 

 processes is quite obvious (see pp. 81 and 272). FREI and MARGA- 

 DANT have determined similar relations between both the increased 

 activity of cresol soap solutions by salts of the light and of the heavy 

 metals as well as the decreased surface tension induced by such salts. 



We may imagine that there is yet another possible way for salts 

 or other substances to exert an influence by their mere presence. 

 H. BECHHOLD and ZiEGLER* 2 showed that the permeability of jellies 

 was influenced by certain substances, and from this we may assume 

 that the permeability of the bacterial plasma pellicle for a disin- 

 fectant may be changed by the presence of a third substance. 



This assumption is reinforced by experiments of EISENBERG and 

 OKOLSKA which showed that alcohol, alkalis, urea and some other 

 substances, which increase the permeability of jellies, also increase 

 the disinfectant activity of many antiseptics. 



In practice the conditions are complicated enormously. We are 

 no longer concerned with the distribution of the disinfectant between 

 solvent and microorganisms but organic substances are added 

 (sputum, albumin, feces) so that we have the sums of unknown 

 factors which can only occasionally be resolved. The action of a 

 disinfectant is usually much depressed by organic matter. This is 

 also the reason why disinfection of the organism, an internal disinfec- 

 tion or antisepsis, has so seldom been accomplished by chemical 

 means. There are, indeed, substances so slightly toxic, that men or 



