Ꮲ Ꭺ Ꮲ Ꭼ Ꭱ Ꮪ Ꭱ Ꭼ Ꭺ Ꭰ . OPTICAL METHODS OF ESTIMATING SUGAR IN MILK. By Prof. H. W. WILEY, Agricultural Department, Washington, D. C. [ABSTRACT.] THE paper contains a review of the determination of specific rotary power of milk sugar and fixes this number at 52.5 (a), as the one nearest the true power. Extensive experiments are described with various reagents for precipitating the milk albumen in which it is shown that the commonly accepted method by basic lead acetate is wholly unreliable. It is further shown that perfectly reliable results can be obtained by using acid mercuric nitrate or mercuric iodide acidified with acetic acid. The paper also compares the results thus obtained with those reached by evaporating the milk to dryness and extracting sugar with aqueous alcohol. By numerous combustions with soda lime it is shown that the basic lead acetate does not remove all the albumen from milk, but that there is left in solution as much as .25 per cent of these bodies. Since they are all laevorotatory, the effect of their presence is to make the dextrorotatory power of the lactose appear too small. Similar combustions show that while the mercury reagents do not remove all the albumen, yet they do so to such a degree as to reduce their disturbing effects to a minimum and render them negligible. The paper closes with directions, based upon the experiments given, for making optical analysis of sugar in milk which are both reliable and speedy. The complete paper is in vol. 6 No. 5, of the American Chemical Journal. ON CHLORPROPIOLIC ACID AND CERTAIN SUBSTITUTED ACRYLIC AND PROPIONIC ACIDS. By Prof. C. F. MABERY, Case School of Science, Cleveland, Ohio. [ABSTRACT.] By treating chlorbromacrylic acid with baric hydrate under carefully regulated conditions, I find that the elements of hydrobromic acid may be eliminated with the formation of chlorpropiolic acid. Although this acid has not yet been obtained perfectly pure, its identity is established by the formation of addition-products with hydrobromic and hydriodic acids both of which have been analyzed. The chloriodacrylic acid thus obtained melts at 84°-85° and the chlorbromacrylic acid which is probably identical with the acid from which chlorpropiolic was prepared, at 68°-70°. In 1879 Wallack mentioned briefly the formation of chlorpropiolic acid beside dichloracrylic acid as one of the products of the decomposition of chloralid but no attempt was made to prepare its addition-products. I have also observed that chlorine is readily absorbed by chlorbromacrylic acid and at ordinary temperatures the formation of the addition-product is complete in a few hours. The resulting bromtrichlorpropionic acid forms an oil with water and is quite soluble in carbonic disulphide from which it separates when cooled to 0° in prismatic crystals which melt at about 80°. By the action of baric hydrate in aqueous solution the elements of hydrobromic acid are removed forming trichloracrylic acid with a melting point of about 75°. The elements of hydrobromic acid are easily eliminated from both a and dibromdichlorpropionic acids with the formation of the corresponding bromdichloracrylic acids. These acids both melt at 78°-80° and although their salts show certain differences in their water of crystallization the acids themselves have not been sufficiently studied to determine whether they are different or identical in form. CONTINUOUS ETHERIFICATION. By Dr. L. M. NORTON AND C. O. PRESCOTT, Mass. Institute of Technology, Boston, Mass. SINCE the examination of the process of continuous etherification by Williamson,1 and the explanation of it in his classical research, our knowledge of its possible applications has made no material progress. The formation of ethers by the action of sulphuric acid upon alcohols has found practical application only in the manufacture of ethyl ether in the manner proposed by Boullay2 before the 1 Ann. d. Chem.v.77, 37, and v. 81, 73. 2Jour. Phar. v. 1, 96. course of the reaction was understood, and in the manufacture of methyl ether,3 which is now used extensively for cooling purposes. We have re-examined the formation of ethyl ether by this process in order to fix more carefully the limits of temperature within which the reaction can be effected, and also the temperature at which etherification is most complete, and we have also investigated the behavior of propyl, isobutyl and isoamyl alcohols when subjected to the process of etherification. We have examined also the formation of mixed ethers by this process. Ethyl Alcohol. The apparatus used in all the experiments described below was essentially that originated by Boullay, and afterward used by Williamson. It consists of a two-litre flask, with a wide mouth closed by a cork through which passes a thermometer, a dropfunnel, and a delivery tube leading to a condenser cooled continually with ice water. In the first series of experiments 200 grams of commercial 90 per cent. alcohol were subjected to etherification in each experiment. Twenty grams of alcohol were mixed with 36 grams of ordinary strong sulphuric acid, placed in the flask, which was then heated to the desired temperature in an oil-bath, and the mixture was maintained at the desired temperature while the remaining alcohol was slowly added through the drop-funnel. It is evident that if the distillate was subjected to fractional condensation and the undecomposed alcohol returned to the generating flask and only the ether collected, in sufficient time the alcohol would be changed to ether, even at a temperature far too low for advantageous etherification. As we desired to examine the amount of alcohol changed to ether at different temperatures, we allowed the ether and undecomposed alcohol to distil together from the generating flask, and subsequently subjected the distillate to fractionation. The distillates from temperatures below 160° were free from sulphurous anhydride. They were treated with solid caustic potash to remove any traces of sulphuric acid and then distilled from quick-lime. After three fractionations, the portions boiling between 35° and 45° were weighed. In these experiments 163 grams of pure ethyl alcohol were available for etherification. Tellier, Arch. Phar. v. 16, 57. A second series of experiments was now made, and the distillates were fractionated with the utmost care. In these experiments 150 grams of 90 per cent. alcohol were used, and 118 grams of ethyl alcohol were available for etherification. The specific gravity of the ether obtained was 0.744 at 0° compared with water at the same temperature. This specific gravity would indicate the presence of a minute quantity of alcohol in the ether. These results would indicate that the action of alcohol upon ethylsulphuric acid begins at a temperature much lower than has been supposed, rises in rapidity and completeness until the temperature of 145° is reached, where the maximum yield of ether is obtained. Above 150° the yield begins to lessen, and doubtless the formation of ethylene begins, but the yield does not diminish greatly until 160° is reached. At 160° the formation of sulphurous anhydride begins and numerous gaseous products are evolved, and the sulphuric acid is soon destroyed, as has been observed by others. Ether continues to be formed above 160° in small quantities, and, according to Mitscherlich,5 is even found among products formed at 200° and above that temperature. Gmelin, Handbuch v. 4, 552. Ann. Ch. Phys. v. 3, 7, 12 Propyl Alcohol. We were unable to find any evidence that this alcohol was ever subjected to the process of continuous etherification. We took 50 grams of propyl alcohol for our experiment. Fifteen grams were mixed with 20 grams of sulphuric acid, the mixture heated at 135°, and the remaining alcohol added in the usual way. A colorless distillate was obtained, at the same time there was a slight evolution of sulphurous anhydride and a slight deposition of tar in the generating flask. The distillate was treated with solid caustic potash, then distilled from lime, and was found to boil between 80° and 90°. It was next washed with water, distilled again from lime, and then allowed to stand with sodium until all action ceased. Its boiling point was then between 82° and 84°; it possessed a strong ethereal odor, and agreed in all respects with the propyl ether described by Chancel and Linneman.7 The yield is very good, and this method will prove the most convenient for the preparation of propyl ether. Isobutyl Alcohol. It is well known that at a high temperature sulphuric acid withdraws water from isobutyl alcohol and produces isobutylene. We have subjected isobutyl alcohol to the ordinary process of continuous etherification at 120° and also at 135°. In both cases sulphurous anhydride was freely evolved, and tar remained in the generator. A yellowish distillate was obtained, which upon purification and fractionation proved to consist of undecomposed isobutyl alcohol. We were unable to obtain any appreciable quantity of isobutyl ether. Isoamyl Alcohol. We next investigated the behavior of isoamyl alcohol under the ordinary conditions of continuous etherification. At temperatures very little above 100° a violent action begins, and sulphurous anhydride is freely evolved. Before the temperature of 140° can be reached the sulphuric acid is destroyed, and only tar remains in the generator. As isoamyl ether boils at 176° it is evident that it cannot be produced by this method. Below 140° a distillate was 'Linneman, Ann. d. Chem. v. 161, 37. Ann. d. Chem. v. 151, 304. Lermontoff, Ann. d. Chem. v. 196, 117, et al. |