140 Journal of Agricultural Research voi. xvii, no. 4 



in the necks of the flasks to condense the alcohol and the mixture was 

 allowed to boil 30 minutes. While still hot, the flasks were made up to 

 the mark with 95 percent alcohol and allowed to stand over night. They 

 were then shaken, again made up to the mark, tightly stoppered, and 

 stored. The final strength of the alcohol in which the samples were stored 

 was about 64 per cent. 



When a large number of samples are taken during a comparatively 

 short time, as was the case in this work, it becomes necessary to store 

 most of the samples for some time. Since the storage problem is an 

 important one, a number of experiments were conducted to determine 

 the best treatment of the samples to prevent any carbohydrate changes 

 during long periods of storage. The final method, previously described, 

 was found to preserve the samples for at least 145 days without any 

 appreciable carbohydrate changes. After boiling, the samples may be 

 safely stored in 50 per cent alcohol. Cold treatment of the sam.ples 

 with 52 per cent alcohol inhibited invertase action, but there was con- 

 siderable starch hydrolysis after a long period of storage. If the number 

 of volumetric flasks is limited, a measured quantity of the filtered extract 

 can be stored. In this work 150 cc. were frequently stored. 



The method employed for the determinations of the sugars in the 

 solutions was essentially the same as the one described by Bryan, Given, 

 and Straughn.^ 



Starch. — Ten gm. of the mash were weighed into counterpoised 200 

 cc. Erlenmeyer flasks and immediately covered with 50 cc. of 95 per cent 

 alcohol. About 0.05 gm. of calcium carbonate was added and after 

 thorough shaking the flasks were tightly stoppered and stored. The 

 strength of the cold alcohol in the mixture was approximately 80 per 

 cent. This was found sufficient to preserve the samples for several 

 weeks without any appreciable change in the carbohydrates present. 

 The method of weighing out the samples in small flasks, counterpoised 

 on torsion balances sensitive to one-fifteenth gm. was found to give 

 just as good duplicates as weighing the samples to the third place in 

 weighing bottles. By the former method, the samples could be placed 

 in alcohol in a very much shorter time. 



The determinations were made according to the following procedure: 

 Decant the preserving alcohol on to a 9 cm. No. 1 Whatman filter paper; 

 add 75 cc. of 50 per cent alcohol and extract 24 hours at room tempera- 

 ture, shaking noon and evening; decant completely the 50 per cent 

 alcohol; add 50 cc. more of the 50 per cent alcohol and allow to stand 

 two hours, shaking three times; decant the alcohol and when all has 

 run through the filter transfer the mash to the filter; apply suction 

 and drain; add 50 cc. of 50 per cent alcohol to the flask to wash down 



1 Bryan, A. Hugh, Given, A., and Straughn. M. N. extraction of grains and cattle foods 



FOR THE determinations OF SUGARS; A COMPARISON OF THE ALCOHOL AND THE SODIUM CARBONATE 



digestions. U. S. Dept. Agr. Bur. Chem. Circ. 71, 14 p. ign- 



