PRESERVATION BY SALTING 499 
in food preservation. As methods for its manufacture were developed 
it became too abundant for currency and gradually was used for preser- 
vation of foods. Different reasons have been ascribed for the keeping 
power of salt. 
I. Exerted a poisonous action. 
II. Made the moisture unavailable for the microorganisms. 
III. Destroyed cells by plasmolysis. 
Rapin and Weigman (1913) found that salt contained bacteria. Salt 
which was kept in barrels had a high number of bacteria in the upper 
layers. Spore-forming varieties were found which would attack milk 
fat when this was salt used dairying. 
Peterson (1900) reported some interesting data from which the 
change of species of microorganism with salt concentration may be 
noted. In low concentrations the flora is more heterogeneous. Between 
12 and 15 per cent concentration the rods are killed. Wild yeasts 
develop in 25 per cent of salt. These data were secured from studies on 
fish. (See Table 48.) 
TABLE XLVIII 
INFLUENCE OF SALT UPON THE BACTERIAL FLORA AND DECOM- 
POSITION OF FISH 
(Peterson, 1900) 
The figure indicates the day after salting when bacteria or chemical change was 
first noticed. 
Seamanaiil 
Per Per Per Per Per Per Per Per 
Cent. | Cent. | Cent. | Cent. | Cent. | Cent. | Cent. | Cent. 
TS | a | WLAN | in | siete | CEHEAetrirSrEnee | SrTS/TRAriinsiitimnee | SOARES ay 
Salt concentration...... 
5 8 10 12 15 18 20 23 
Rods, appear.......... 2 14 23 52 
Rods, plenty........... 12 29 50 75 
Cocci, appear.........- 2 2 2 2 14 15 50 75 
Cocel, plenty.......... 2 2 6 6 34 15 
Yeast, appear... ...... cece ee efe eee ele ee eee 6 14 15 50 75 
Yeast, plenty. ....... 00). . cee fee c eee le ee ee ele ee eae 14 15 
Odor. ...... cece eee eee 6 8 8 12 34 75 
Alkaline reaction ...... 4 6 10 12 34 69 
Butyric acid........... 12 23 23 12 34 75 75 
Peptones.............- 10 |...... 30 58 75 75 
Ammonia.............. 7 6 10 12 
HaS.. cece ee eee 6 14 28 58 
Indol.. 2... eee eee 16 29 68 75 
Phenol....-...e.e2-00- 55 75 
The blank spaces indicate that change was not observed in seventy-five days. 
