I 1920] AGRICULTURAL CHEMISTRY — AGROTECHNY. 317 



author (liscusscs briefly the utilization of dcliydratiuu in various countries and 

 tlie results of previous invesli^iations on some of tiie bioloj,'ical questions in- 

 volved in this process of food preservation, and presents the results of bac- 

 teriolof,'ical studies on the commercially dehydrated veK<^tables used by the U. S. 

 Army during the recent war. These studii's Included determinations of tlio 

 amounts of bacteria and molds on different kinds of vefretables and fruits, the 



effect of storage in various containers and under different conditions of tem- 



« 

 perature and humidity, and the effect of dehydration upon ori,'anisms commonly 



associated with food poisoninj;:. 



From the standpoint of numbers and types of bacteria, the commercially de- 

 hydrated i>roducts were found to have the ijame characteristics as raw fruits 

 and vej,'etables except that the number of organisms was much less than on 

 the fresh article. The predominating t.vpes of bacteria were those having their 

 habitat in soil or water. Seven genera of molds were isolated, including two 

 species of Mucor, two of Penicillium, and five of Aspergillus. 



In the investigation of the efl"('ct of environment on the bacteriological char- 

 acter of the foods in different containers, four types of storage conditions were 

 employed in which the humidity was at 100, 70, 50, and 95 per cent, with the 

 corresponding temperatures 37° C, 20 to 25°, 37° and ordinary temperature, and 

 0°, respectively. Materials stored in tin and glass containers under all condi- 

 tions of temperature and moisture remained practically constant in their con- 

 tent of moisture and molds, while the bacterial counts diminislied either rapidly 

 or slowly. Samples stored in paper containers, whether parafiin treated or not, 

 \mder conditions of higher temperature and humidity showed a decided increase 

 in moisture and in bacteria and mold count at the end of 6 weeks. Similar 

 results were obtained in cold storage (0°, 95 per cent humidity), while at ordi- 

 nary temperature and dry atmosphere a decrease in moisture and bacterial 

 count resulted, the mold spores remaining practically constant. These results 

 are considered, to prove beyond doubt that paper or wood pulp containers of 

 good quality may be safely used in temperate zones, but are not suitable for 

 use in hot moist conditions. 



I'reliminary results obtained in a series of experiments in whicli vegetables 

 were inoculated with pathogenic organisms associated with food poisoning and 

 were then subjected to dehydration in the laboratory and in a connnercial de- 

 hydrating plant indicate that these pathogenic organisms are, in general, de- 

 stroyed by the process of dehydration, and consequently that the danger of 

 poisoning from contamination of the vegetables before dehydration is slight. 



Practical leather chemistry, A. Hakvey {London: Crosbi/ JjOcJxirood d Son, 

 1920, pp. [8]+207, pi. 1, fiffft. 9). — ^This laboratory manual, which has been de- 

 signed particularly for chemistry students specializing in the leather industry, 

 consists of methods of chemical analysis as applied to materials used in the 

 tanning, dyeing, and finishing of leather. 



The grasses of the Eastern Coast IJelt available for the manufacture of 

 paper, and the possibilities and prospects of paper making in the Union 

 of South Africa, C. F. .Turitz ([Union So. Africa, Min. Mines and Indus.], 

 Indus. Bui. Ser., No. 7 (1919), pp. IV-{-115). — This bulletin consists of reports 

 of an investigation of the paper-making possibilities of various grasses of the 

 Eastern Coast belt of South Africa and of the commercial prospects for such 

 an industry. These are followed by appendixes consisting of an historical 

 review of previous investigations along the same lines, notes on technical 

 points in connection with paper making, brief descriptions of a large variety 

 of raw materials in addition to grasses which have be(Mi suggested as suitable 

 for the maiuifacture of paper, a discussion of the paper industry in various 

 countries, and an extensive bibliography.* 



