156 PROVISIONAL METHODS FOR ANALYSIS OF FOODS. 



liquid after every other cubic centimeter and putting the point of it upon a piece of 

 litmus paper. After the absorption of the liquor from the tube the center of the blot 

 will show the alkaline blue on red litmus paper before a drop will. This method was 

 brought before the local section of the American Chemical Society some years ago by 

 Dr. S. Waldbott. B. M. Pilhashy. 



Page 84, 10. Allow me to call attention to a point that is often overlooked in the 

 examination of fermented and distilled liquors. The determination of glucose in 

 wines, etc., is often based on the examination of the sample for dextrine. This in 

 itself is all right except that very little commercial glucose is used in any fermented 

 liquor except beer. The product that is used is grape sugar, which has been so 

 highly converted that it will not give more than a qualitative test for dextrine. The 

 only way to determine the presence of grape sugar is by double polarization before 

 and after inversion. Nor is this positive proof of adulteration since, in some cases, 

 invert sugar is used besides grape sugar, and the amounts are so well balanced that 

 the polarization due to these two products is 0, In cases of this kind the addition 

 of the foreign bodies can only be determined indirectly. The cane sugar is deter- 

 mined by reduction before and after inversion, the difference between the two 

 results being calculated to cane sugar. The direct reduction is then due to the mix- 

 ture of the grape and invert sugars. A mixture of about one part of grape sugar to 

 to 2 parts of invert sugar will give a direct polarization, and a polarization after 

 inversion of 0. In some cases I have found that direct polarization was due to the 

 cane sugar added. This is only the case where the fermentation was complete and 

 all the sugar of the grape turned into alcohol. 



The point that I want to bring out is that a certain relation exists between the 

 amounts of sugars found by polarization before and after conversion, and the amounts 

 of reducing sugars found by the reduction method before and after conversion, and 

 that the absence of this relation is always proof of adulteration due to the addition 

 of grape or invert sugar or both. Edward Gudeman, 



BAKING POWDER AND BAKING -POWDER CHEMICALS. 



Page 98, 1. Regarding the determination of carbon dioxid, I will say that I have 

 used for factory control work a method which requires for its execution a slight 

 modification of the Kjeldahl nitrogen apparatus, receiving the distillate in a solution 

 of sodium hydroxid whose titre of free alkali is known; afterwards titrating with 

 standard acid, using phenacetolin as the indicator. I am satisfied that with the 

 cooperation of the association this method could be made as good for carbon dioxid 

 as the Kjeldahl is for nitrogen. 



Figure 7 illustrates the apparatus used by myself for the estimation of carbon dioxid 

 in low-grade phosphate rock, such as is used for fillers in the manufacture of com- 

 mercial fertilizers. 



The flask C is an ordinary globe chemical flask having a capacity of 1,000 cc, fitted 

 with a funnel tube having a stopcock at B. The flask E is an absorption flask having 

 two bulbs, as shown. It should have a capacity of about 200 cc. The condenser D is a 

 Liebig condenser of brass, with inner tube of block tin, as used in the Kjeldahl nitro- 

 gen process. This tin tube is connected with the bulb tube of flask C by a bitof rub- 

 ber tubing and terminates in a glass tube which is fitted by a rubber stopper to flask E. 



The determination is made as follows: Place 500 cc of freshly boiled distilled water 

 in flask C; allow it to cool, and, if convenient, reduce its temperature to 20 or 

 lower; then introduce into flask C about 1 gram of the substance to be estimated. 

 Place in funnel tube a quantity of normal sulphuric acid considerably in excess of 

 that required to decompose the substance. Place in the flask E 50 cc of normal or 

 double normal sodium or potassium hydroxid solution. The exact content of 

 hydroxid in this solution must be determined by titrating with decinormal sulphuric 

 acid and phenacetolin previous to using it in a separate, portion, of course. 



