THE SALTING OF FISH. 



25 



chloride as impurity is sufficient to produce a very stiff, hard fish. 

 One per cent of calcium chloride produced a softer fish, but yet one 

 which was much harder than that produced by pure sodium chloride. 

 Four and seven-tenths per cent of magnesium chloride, as impurity, 

 produced a fairly hard, stiff fish, with a very bright, shiny appear- 

 ance. . ... 



Both calcium chloride and magnesium chloride, as impurities in 

 salt, caused a very noticeable whitening. This whitening could easily 



1 



3 



a 



10 



Fig. 1.- -Curv<'» sliow retardation of penetration of salt duo to 1 ixr leni. of calcium 

 chloride impurity (section J to 1 cm. depth). Figures at left Indicate per cent of 

 chlorine iu dry Ush ; at twttom, time Iji days. 



bo followed, as it was first observed in the outer portions of the fish 

 and moved toward the center until at the end of from 10 to 13 days 

 the fish was uniformly white throughout. Calcium chloride was 

 most active in this regard. 



Figures 1 to 4 iUus-trate graphically the data presented in the 

 tables. In each case the time in days is plotted along the ordinate 

 (horizontal line). The percentage of chlorine in the dry fish is 

 plotted along the abscissa (vei-tical line). 



Figure 1 shows how the porcontage of chlorine in fish (the amount 

 of sotlium chloride contained in the fish) increases for 10 days. The 



