May 2, 1913] 



SCIENCE 



675 



ducted to the various places of interest in Madi- 

 son. The chemical laboratories of the University 

 of Wisconsin, the capitol and the forest products 

 laboratory were visited. A luncheon was served to 

 the visitors, at which President Van Hise presided. 



All members of the society who went to the 

 Milwaukee meeting were well repaid for the 

 journey. 



The following is a list of papers presented, with 

 abstract where abstract was furnished: 



GENERAL MEETING OF ALL DIVISIONS AND SECTIONS 



Joel H. Hildebrand: Some Applications of the 



Hydrogen Electrode in Instruction, Analysis and 



Sesearch. (Illustrated.) 



The chaEge of hydrogen or hydroxyl-ion concen- 

 tration during the neutralization of acids and 

 bases, the precipitation of hydroxides, etc., gives a 

 very remarkable insight into the nature of the 

 reaction. This change can be followed by means 

 of the hydrogen electrode, of which a simple form 

 was described, together with apparatus allowing 

 its potential to be easily determined with a volt- 

 meter. Curves were thrown on the screen showing 

 the variation of potential, and consequently of 

 hydrogen and hydroxyl-ion concentration, during 

 the neutralization of various acids and bases. 

 From these it was pointed out how such things 

 could be easily determined as the proper indicator 

 to use in a given titration, the degree of hydrolysis 

 of salts, the dissociation of weak acids and bases, 

 the way to prepare normal salts where hydrolysis 

 takes place, the effect of structure on the strength 

 of organic acids, etc. Curves representing the 

 titration of salts such as borax and sodium car- 

 bonate were shown and conclusions drawn similar 

 to those just mentioned. Others were shown repre- 

 senting the precipitation of various hydroxides, 

 from which could be drawn conclusions regarding 

 the behavior towards various reagents and the 

 separation from each other. Owing to the differ- 

 ence in solubility of magnesium and calcium hy- 

 droxides, magnesium can be titrated in the pres- 

 ence of calcium, allowing its rapid determination 

 in limestone, etc. The same method can be used 

 with a platinum electrode to determine the 

 oxidizing power of solutions, illustrated by the 

 titration of iron with bichromate, avoiding the 

 use of the external indicator. 

 D. M. Buck: Copper in Steel. The Influence on 



Corrosion. (Blustrated.) 

 H. E. HowE: Some Projection Experiments with 



Spectra. (Illustrated.) 

 Wilder D. Bancroft: The Theory of Emulsions. 



division op agricultural and pood chemistbt 



H. E. Barnard, chairman 



Glen F. Mason, secretary 



H. E. Barnard: The Status of Food Legislation 



in the United States. 



A brief sketch of the history of food legislation 

 in the United States followed by a discussion of 

 the various types of laws, such as the Pure Food 

 Law, Meat Inspection Law, Sanitary Food Law 

 and Cold Storage Law, enacted for the improve- 

 ment and control of the food industry. The spe- 

 cial features of each law are described and the 

 methods employed in their enforcement detailed. 

 Carl L. Alsberg, F. Babak, H. H. Bunzell and 



O. F. Black: Studies upon Maize. 

 W. D. Bigelow: The Equilibrium between Sugars 



and Sulphur Dioxide in Dried Fruit. 



The time required for sulphur dioxide and alde- 

 hydes to unite prevents the formation of this com- 

 pound in fruit that is dried quickly by artificial 

 heat, but permits its formation in fruits that 

 require a number of days for drying. Thus evapo- 

 rated apples are nearly free from sulphur dioxide, 

 while sun-dried peaches and apricots contain con- 

 siderable amounts. The content of the latter is 

 much greater because of the practise in the pack- 

 ing-house of dipping the dried fruit in water and 

 again sulphuring and packing in boxes without 

 subsequent drying. 



The gradual disappearance of sulphur dioxide 

 in dried fruit depends on temperature and hu- 

 midity. The dextrose sulphurous acid compound is 

 quite stable but is broken up by water to a suffi- 

 cient extent to form an equilibrium between this 

 compound and the free sulphurous acid. The free 

 acid is subject to evaporation and oxidation and 

 the equilibrium is, of course, maintained by the 

 hydrolization of an additional amount of the 

 compound. 

 W. D. Bigelow: The Influence of CooTcing on the 



Sulphurous Acid Content of Dried Fruit. 



The methods usually employed in cooking fruit 

 were ascertained by 525 letters of inquiry sent to 

 residents of 21 states. The usual method appears 

 to be to soak a number of hours without previous 

 washing and cook for one or two hours in the 

 water in which it is soaked. During the cook- 

 ing about 10 per cent, of the sulphur dioxide 

 present is oxidized to sulphate and 25 to 35 per 

 cent, of it is volatilized. Preliminary washing 

 removes 2-3 per cent, of the sulphur dioxide, and 

 35-50 per cent, more is removed when the fruit 

 is soaked overnight in two or three times its- 

 weight of water and the latter is poured oflf and 



