258 EXPERIMENT STATION RECORD. 



cium pentasnlpbid decomposes rapidly under the influence of the atmosphere 

 after being sprayed on trees and acts energetically as an insecticide. While 

 calcium thiosulphate decomposes more slowly, the continued action of the in- 

 secticide long after its application is apparently due to this latter compound. 

 The author believes that the cheapest fornuila for the preparation of lime- 

 sulphur wash is 1-1— t. 



Spray for profit (OAlalioiiia ,St(i. Rpf. VJIk;. pp. .'i',-o.',). — Directions are given 

 for the choice, preparation, and application of insecticides and fungicides for 

 controlling insect pests and fungus diseases of fruits, garden vegetables, cereals, 

 shade ti-ees, ornamental plants, and cotton. 



Silk industry {Mo. Consular and Trade Rpts. [U. »S'.], 1906, No. 305. pp. 

 185-190). — A statistical account is presented regarding the extent of the silk 

 crop in various countries, including Italy, Austria, Syria, Greece, Persia, and the 

 far Orient. Notes are also given on the methods of growing the mulberry and 

 care of silkworms. 



FOODS— HUMAN NUTRITION. 



Eopiness in flour and bread and its detection and prevention, E. J. Wat- 

 kins (Jour. ^oc. Chcni. Indus., 25 (1906), No. 8. pp. 350-357, pi. i).— Experi- 

 ments are reported and data summarized regarding the causes of ropiuess in 

 bread, the ways in which ropiness is conveyed, and methods of prevention. 



The trouble is produced by varieties of Bacillus mcscntericus introduced into 

 the dough through the flour where it sometimes occurs in large numbers, pos- 

 sibly coming from the bran coats. Breads containing bran and straight grade 

 white flours nre most liable to develop ropiness. The bacillus is a prolific spore 

 former, and the spores are capable of resisting high temperatures for long 

 periods. The development of the bacillus, when once present in the dough after 

 bread has been made, depends partly on the reaction of the bread and partly on 

 atmospheric conditions. 



The presence of acid is unfavorable to the development of bacillus, but normal 

 bread is only faintly acid in reaction and always insufficiently so to prevent the 

 development and spread of ropiness. The author's experiments led to the con- 

 clusion that " the addition of a small quantity of acetic acid to the dough will 

 effectually prevent the appearance of ropiness in the resulting bread during a 

 much longer period than bread is usually kept. The minimum quantity of acid 

 appears to be about 0.8 lb. per sack of flour, whilst a maximum of 0.7 lb. should 

 not be exceeded on account of its softening action upon the gluten. When lactic 

 acid is employed as a preventive, the minimum quantity is greater ; below O.G 

 lb. per sack its action is somewhat uncertain. ' The greater softening action of 

 this acid ujion gluten must not be lost sight of when considering the quantity 

 to use." 



" Low temperature and dryness of the bread store tend to suppress develop- 

 ment, but the maximum temperature of 18° C. (G.5° F.) can not be exceeded 

 without great risk. 



" When a batch of bread is found to be ropy, all flour in stock should be at once 

 tested, so as to locate the infected stock, and in the meantime fresh supplies of 

 flour from a different source should be laid in. 



" When the infected batch of flour has been discovered, it should be isolated, 

 so that it can be worked up under those conditions which are most unfavorable 

 to the development of the bacillus, i. e., the doughs being made slightly acid and 

 the bread being quickly cooled and kept at low temi)erature during storage. 

 Such flour might advantageously be kept until the colder months when the pros- 

 pects of development are at a minimum. 



