1917) AGRICULTURAL CHEMISTRY — AGROTECHNT. 715 



varieties — citric probably predominates in others with small amounts of malic ; 

 pomegranate, probably all citric, no malic nor tartaric ; quince and watermelon, 

 malic, no citric; and raspberry (red), probably citric only — malic, if present, 

 in traces only. Apricots, blackberries, and huckleberries were also examined, 

 but no definite results on their acid content were obtained. 



The danger of drawing general conclusions as to the acid content of fruits 

 from analysis of a limited number of varieties, or even samples, is indicated as 

 being emphasized by the varying results obtained with pears. 



A table giving results and references thereto as to the acids in various fruits 

 reported by previous investigators is included. 



Sources and composition of some commercial invert sugar sirups with 

 notes on sorghum sirups, S. Jordan and A. L. Chesley {Jour. Indus, and 

 Engin. diem., 9 (1911), No. 8, pp. 756-758).— This is a general discussion of the 

 topics of methods of analysis, moisture-holding properties, specifications, and 

 sorghum sirup. Analytical data, including invert sugar, sucrose, and ash of a 

 number of sirups collected from various sources, are submitted. 



Belative value of different weights of tin coating on canned food con- 

 tainers {Washington, D. C: Nat. Canners Assoc, 1911, pp. 51+666, figs. 9).— 

 This is the report of an investigation by a technical committee representing the 

 National Canners' Association, the American Sheet and Tin Plate Company, 

 and the American Can Company. Products from various parts of the country 

 typical of those usually canned in tin were used. In general, no great differ- 

 ences in the products were observed by using tins with varying weights of 

 coating. 



Data relative to the discoloration of cans and average tin content of various 

 products are submitted in graphical form. Other experimental and analytical 

 data of the investigation are reported in detail in 10 appendixes. 



War food, Amy L. Handy {Boston: Houghton Mifflin Co., 1911, pp. IX+16, 

 figs. 2).— This small volume gives directions for drying fruits and vegetables; 

 preserving meat; canning with and without sugar; preparing jellies; salting; 

 pickling; and making cider, potato, and corn vinegar. 



The evaporation of fruits and vegetables, J. S. Caldwell {Washington Sta. 

 Bui. 148 {1911), pp. 1-111, figs. 26). — This is in part a revision of the bulletin 

 previously noted (E. S. R., 35, p. 418), with new sections discussing in detail 

 the drying of cherries, berries, peaches, apricots, prunes, and various vegetables, 

 together with directions for preparing the materials for drying and for storing 

 and packing the dry products. 



A new method for the preparation of pectin, J. S. Caldwell {Washington 

 Sta. Bui. IJft {1911), pp. 3-14). — A method of preparing pectin from cull apples 

 or other fruits rich in the substance for future use in jelly making from fruit 

 juices poor in pectin is described. The method consists essentially of the sepa- 

 ration of a portion of the water of the juice by freezing, removal of the con- 

 centrated liquid from the ice by centrifugalization (or draining through mus- 

 lin), and repetition of the process until the desired concentration has been ob- 

 tained. The concentration is finally completed by evaporating the residue at a 

 low temperature. The method has been simplified and adapted so that it may 

 be easily carried out with very little equipment. 



The concentrated extracts were found to retain their gelatination properties 

 perfectly after long periods if the acid was removed from the juice by calcium 

 carbonate. A tasteless and odorless dry product may be secured by precipi- 

 tating the pectin from the concentrated extract by alcohol and subsequently 

 drying at a low temperature. 



Some general notes on the occurrence, distribution, and use of pectin are in- 

 cluded. 



