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milk and sulphur were placed, for purposes of control. After the tubes 

 had been well shaken, strips of filtering paper impregnated with a 

 solution of sugar of lead, were pressed in the openings by means of 

 plugs of cotton wool. These plugs at the same time prevented the 

 entrance of bacteria from the air to the milk. It was, namely, desir- 

 able that the milk should contain as nearly as possible the same bac- 

 terial flora. For this reason the milk was always obtained from the 

 same place, kept in the same manner without special precautions, and 

 worked up at the same time after obtaining it. The tubes were left 

 standing for 24 hours in a water-bath of 38 to 40 °C. On the following 

 day an examination was made, whether or not the added substance 

 had prevented the blackening of the lead paper, i. e., whether or not 

 it had acted as an antiseptic. 



Next, the number of drops required to prevent the blackening 

 were read off. From the number of drops belonging to one cc, the 

 volume proportionate to the milk was then calculated, and the con- 

 centration and the intensity of the antiseptic action thereby determined. 

 According to their intensity, the antiseptics were placed in five groups, 

 as shown by the following table: 



The development of H 2 S is 

 prevented by a dilution of: 



The antiseptic power was 

 designated as: 



below 1 in 10 



very feeble 



1 in 10 to 1 in 25 



feeble 



1 in 25 to 1 in 50 



medium strong 



1 in 50 to 1 in 100 



strong 



above 1 in 100 



very strong 





This systematic division has also formed the basis of the table 

 of substances examined. 



The reader will perhaps be astonished that Bruning and I cha- 

 racterise the antiseptic power as very strong if it is above 1 in 100, 

 whilst in many experiments mentioned in literature, a very strong action 

 is only spoken of at 1 in 10 000. This apparent contradiction can thus 

 be explained, that in all series of experiments in which it is desired 

 to obtain the best results for an antiseptic, a medium is selected 

 which impairs the antiseptic power as little as possible, and which 

 promotes the vitality of the microbes to the least possible extent. But 

 in our experiments purposely the opposite conditions were selected, 

 for on the one hand, we used the most favourable possible nutritive 

 medium for the milk bacteria, viz., raw milk, — and on the other 

 hand, the total quantity of the essential oil added, which in being 

 dissolved in the milk passed over in the fat globules of the latter, was 

 abstracted from the aqueous solution, and was thus prevented from 

 acting in that aqueous solution which contained the bacteria. Just for this 



