36 THE SALTING OF FISH. 



down the fish and keep them covered. The fish are not disturbed 

 until the end of the salting period. 



In the brine method of salting fish the procedure is as follows: 

 Fish are dumped into a vat containing enough brine nearly to cover 

 them, and a considerable quantity of talt is added along with the 

 fish. Each day more salt is added, and the fish are stirred in the 

 "pickle." The purpose of adding the salt is to maintain the brine 

 as near saturation as possible. 



In these experiments these two methods were given a trial. The 

 commercial methods were imitated as closely as possible in order to 

 fairly compare the methods. 



DETERMINATION OF RATES OF PROTEIN DECOMPOSITION. 



METHOD. 



Ninety pounds of reasonably fresh squeteague {Cynoseion regalis) 

 were obtained. The fish had been caught two days previously and 

 had been kept on ice. There were 120 fish in all, making the aver- 

 age weight three-fourths of a pound. They were cut down the 

 belly and e^ascerated. The tails and heads were cut off, and the 

 fish were washed in ice water. 



After cleaning there remained 23.4 kg. of fish. These were divided 

 into 12 lots. Six lots of 1.3 kg. each and six other lots containing 

 2.6 kg. each were weighed out. To each of the smaller lots were 

 added 1,300 c. c. of saturated sodium chloride solution and 250 

 grams of pure, dry sodium chloride. The fish of the larger lots 

 were rubbed in chemically pure dry salt and then packed in 

 glass dishes, cut surface down, and sodium chloride was sprinkled 

 over each layer. The 2.6 keg of fish just made two layers; 990 

 grams of salt were used in this way on each lot. The salt used in 

 this experiment was chemically pure " Baker's analyzed " sodium 

 chloride. This salt is a little smaller grained than " ground alum." 



One of each of the lots of fish was then placed in a different con- 

 stant-temperature compartment. The fish were permitted to remain 

 in this constant-temperature apparatus for nine days. The brine- 

 salted lots of fish were stirred daily. The temperature in any one 

 compartment did not vary more than 1° F. from the average. The 

 brines were sampled and analyzed for amino-acid nitrogen on the 

 first, third, fifth, seventh, and ninth days. At the end of the experi- 

 ment the fish and salt were also analyzed for amino-acid nitrogen. 

 In the case of fish to which the brine had been added not more than 

 25 grams of salt remained undissolved. The amount of amino-acid 

 nitrogen in this small amount of salt was considered negligible. In 

 all cases, however, there was an excess of undissolved salt at the end 

 of the salting period. 



The method of sampling the fish, brine, and salt was described 

 in the first section of this paper. The method of analysis of the 

 samples for amino-acid nitrogen was the formol -titration method, 

 which was described on page 29. 



DISCUSSION. 



Table G shows the titration values obtained by the formol titration 

 for amino acids of 25 c. c. of the brines. These figures are given 



