THE SALTING OF FISH. 33 



Lot FA-1 was salted with salt containing calcium chloride as im- 

 purity. This increase in the amount of amino-acid nitrogen formed 

 was about 50 per cent over the weight of amino-acid nitrogen formed 

 when pure salt was used. In other words, there was a half more 

 decomposition of the protein when the salt contained 5 per cent of 

 the calcium chloride than when no calcium chloride was present. 

 Five per cent of calcium chloride is only the equivalent of 1.8 per 

 cent of calcium. This is a greater amount than was contained in 

 any whose analyses are given in the tables of salt analyses. 



Salt sample num])er MD 16102 contained 1.33 per cent calcium. 

 However, it will be noted that the total impurit}^ amounted to 7.3 

 per cent. Lot FA-4 was salted with salt containing 5 per cent of 

 magnesium chloride. In this case 0.380 gram of amino-acid nitrogen 

 was formed during the salting period. This is 15 per cent more than 

 when pure salt was used (FA-5, FA-6). However, 5 per cent of 

 magnesium chloride is 1.28 per cent of magnesium, which is double 

 the amount of magnesium likely to be found in any commercial salt. 



If the salt analyses given previously are consulted, it will be seen 

 that the Trapani salt sample is the only one that contains a very large 

 amount of magnesium and that this amount is less than 3 per cent 

 of total magnesium salts. It seems unlikely, therefore, that the 

 amounts of magnesium salts contained in commercial salts have any 

 appreciable deleterious effect on the fish-curing properties of any 

 salt. 



Effect of sodium sulphate. — Samples DA-8 and DA-9 were pre- 

 pared for salting by cutting off the heads and cutting the length of 

 the abdominal cavity. All viscera were removed with the exception 

 of the milt or roe. As the milt and roe were left in the fish, it was 

 impossible to wash the fish thoroughly, or to remove all the blood. 

 For this reason the maximum temperature of salting was greatly- 

 lowered, even though all other conditions were identical. These fish 

 were salted in brine. For every gram of fish taken 1 c. c. of brine 

 was used. At the time of salting a considerable excess of solid salt 

 was added. From time to time more solid salt was added. The fish 

 were stirred daily. Sufficient salt was added to keep the pickle sat- 

 urated at all times. The amount of salt required for this purpose was 

 about one-fifth of a gram of salt for every gram of fish. 



The samples were taken at the end of the salting period. They were 

 analyzed, and the calculations were made in the manner previously 

 descriljed. Lot DA-8 was salted with nearly pure salt. The salt 

 used in lot DA-9 contained 5 per cent sodium sulphate as impurity. 

 These lots were salted just above the maximum temperature for fish 

 cleaned in this way (containing roe, milt, and blood). Any differ- 

 ences in the preseiwing or penetrating powers of the salts used should 

 show up very noticeably under these conditions. Yet there is only a 

 difference of 7 per cent in the amount of amino-acid nitrogen formed. 

 There is a little more decomposition in the case of the salt containing 

 the sodium sulphate, but the difference is slight. There is usually 

 not more than 2 per cent of sulphates contained in commercial salts. 

 Had the amount of sodium sulphate been reduced to 2 per cent it is 

 likely that the difference between the preservative power of the im- 

 pure salt and the pure salt would have hardly been noticeable. 



