THE BEHAVIOE OP CERTAIN MICRO-ORGANISMS IN BRINE. 



67 



It is clear, then, that the small bacillus which gives to the concentrated brine in the 

 salterns on the shores of the Bay of San Francisco their striking red color, may go over 

 into the salt as it is harvested and stored, and be carried with it into contact with organic 

 matter, forming a suitable medium for its growth. Its growth may be checked or prevented 

 by the addition of preservatives or by keeping the material dry and in dry air. But it 

 certainly does not occur alone in crude salt (or even in salt of a certain degree of refinement) 

 from salterns the brines of which it colors; it is simply the most conspicuous form. Other 

 putrefactive bacteria, presumably more serious in the decompositions which they accom- 

 plish, accompany it and are carried with it into salted cod-fish unless such salt be sterilized. 

 As these bacteria, like the brine algse, are killed by temperatures not fatal to most other 

 organisms, the salt can be sterilized on a commercial scale by low heat and at a cost which 

 would not seem to be prohibitive. In fact, sterilized salts are now advertised in San Fran- 

 cisco by one of the producers, thus proving the realization, on the part of the owners of 

 salt works, that even such a preservative as salt may carry with it its opposite. 



ANALYSES. 



The knowledge that these brines are formed by condensing sea-water pumped from 

 the Bay of San Francisco gives us only a very imperfect idea of their composition, either 

 qualitatively or quantitatively. We know that a great number of substances may be 

 recovered from sea-water by sufficiently refined methods of analysis, but that they all 

 remain in solution, either in the same or in changing proportions, throughout the stages 

 of salt manufacture, is not the case. The ratios, then, of the dissolved salts in sea-water 

 to each other is not the same as in the brine at various stages of its concentration. Thus 

 the sea-water undergoes by evaporation 



Table 23. 



-Analyses of brines (expressed in milligrams 

 per liter). 



No. l 



Sp. gr. 

 1.2321 



No. 2 

 Sp. gr. 

 1.1007 



such concentration that most of its load 

 of calcium is thrown down in the "pickle 

 ponds" or before. The brine pumped 

 from the "pickle ponds" into the num- 

 bered salterns, the organisms in which 

 have been the theme of the foregoing 

 pages, is rich in sodium, magnesium, and 

 potassium, in chlorides and sulphates, 

 poor in calcium, iron, and nitrates; and 

 the final "mother-liquor," the discarded 

 residue from which salt has been har- 

 vested and in which living organisms 

 may still be found, is poor in sodium 

 and chlorine, rich in magnesium, potas- 

 sium, and sulphur. The accompanying 

 quantitative analyses of brines x (table 23), one of high and the other of low specific 

 gravity, make these facts clear. A brine containing upwards of 30 grams of solid matter 

 in every 100 c.c. of water is very concentrated. The specific gravity indicates this, but 

 analysis shows it even more strikingly. 



In addition to a load of dissolved matter equaling one-third of its own weight which 

 the water of these densest brines carry, there is a very considerable amount of suspended 

 matter, much of it organic. This organic matter is of most physiological importance, 

 but I have not been able to have its amount accurately determined, still less its constitu- 

 ents, the difficulties of inorganic analyses being sufficiently great. 



Silica (SiOz) 



Bicarbonate radicle (HCOa) . 



Sulphate radicle (SO*) 



Borax radicle (B4O7) 



Nitrates 



Bromine (Br) 



Chlorine (CI) 



Iron (Fe) 



Calcium (Ca) 



Magnesium (Mg) 



Sodium (Na) 



Potassium (K) 



14.00 



610.00 



30,950 00 



160.00 



trace 



1,000.00 



182,380.00 



4.90 



250.00 



23,330.00 



89,910.00 



6,210.00 



334,818.90 



6.00 



328.00 



10,030.00 



trace 



330.00 



81,513.30 



2.80 



1,429.60 



5,624.20 



45,091.00 



1,610.00 



146,774.90 



1 Made for me by Mr. W. H. Sloan, Instructor in Chemistry in Leland Stanford Junior University, to whom I 

 wish here also to express my thanks. 



