196 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



very light brown, and from 30 to 35 per cent amber, or not decidedly 

 dark. Having been accepted by the inspector, the nuts then go to the 

 bleach. 



BLEACHING. 



Various methods of bleaching walnuts have been practiced, the 

 object being to remove all dirt and discoloration from the shells and 

 give them a bright, light colored, attractive appearance. In the earlier 

 years of the industry most of the nuts were bleached by exposure to 

 the fumes of burning sulphur, this being done while they were wet. 

 Sulphur bleaching is quite unsatisfactory, however, owing to the fact 

 that the fumes penetrate the kernels of the nuts to a considerable 

 extent and have a decided effect upon their flavor. On this account 

 sulphur was largly abandoned several years ago and a process of 

 bleaching the nuts by immersion in a liquid took its place. This process 

 consists essentially in dipping the nuts into a solution of chloride 

 of lime and sal soda, to which sulphuric acid is added, the result being 

 a liberation of chlorin gas which brings about the bleaching action. 

 The following formula which was given out by the University of Cali- 

 fornia Experiment Station illustrates the details of this process : "Six 

 pounds bleaching powder (also called chloride of lime), twelve pounds 

 sal soda, fifty gallons water. Dissolve the bleaching powder in about 

 four gallons of water, stirring till dissolved. Dissolve the sal soda 

 in about four gallons of water. Add one solution to the other and 

 stir well; let the carbonate of lime settle to the bottom and draw off the 

 clear liquor and add water to make a total of fifty gallons. Put the 

 nuts in large dipping box or lath crate, immerse in the fluid, and then 

 add one and one fourth pounds of 50 per cent sulphuric acid and 

 agitate by raising and lowering the dipping box. The bleach should 

 be reached in five to ten seconds, and the nuts are then washed in clear 

 water and put out to dry. Of course to employ this process cheaply, 

 specially contrived dipping appliances are used. The same liquor can 

 be used with new batches of nuts so long as the proper effect is pro- 

 duced, and small additions of acid will prolong the efficiency of the 

 liquor. ' ' 



Owing to litigation over the rights to this process and a decision 

 in the California courts that it was covered by a patent, further efforts 

 were made by the walnut growers to obtain a satisfactory bleach and 

 quite recently they employed Professor Stabler of the University of 

 Southern California, Los Angeles, to devise a new process. Professor 

 Stabler brought into use the electric process, consisting essentially in 

 passing an electric current through a 4 per cent solution of common 

 salt by means of electrodes immersed in the liquid. In this process 

 chlorin is set free and becomes available for bleaching. It is possible 



