BUREAU OF CHEMISTRY. 



267 



tine and Rosin Producers' Association for use in determining their 

 practicability and permanence. Up to the present time reports have 

 fjeen favorable. 



All sets of the standard glass types for rosin were recalled, cleaned, 

 checked against the master set held in the laboratory, and returned 

 to their several depositories for the use of the tiacle. The use of 

 these standards is becoming more general and is serving a most useful 

 purpose. 



WATERPROOFING AND FIREPROOFING FABRICS. 



The weathering experiments started in 1921. wliich were designed 

 to show the effects on the strength and water resistance of cotton 

 duck exposed to weather when various pigments with formulas pre- 

 viously devised in the laboratory' are incorporated, were completed, 

 and a paper giving the results "^has been prepared for publication. 

 In general, it has been found that the addition of pigments to w^ater- 

 proofwig preparations is beneficial since they reduce the injurious 

 effects of solar light and heat without reducing the water resistance. 



A paper on " The water resistance of treated canvas during con- 

 tinuous exposure to weather." which embodies a thorough study of 

 the water resistance of 18 waterproofing treatments developed in the 

 laboratory, was published, and one on "The effects of waterproofing 

 materials upon the tensile strength of cotton yarn" was presented at 

 the Septeml3er meeting of the American Chemical Society. 



In response to a number of inquiries concerning treatments which 

 might be suitable for making " glass cloth " from cotton sheeting for 

 covering hotbeds and cold frames, experiments have been conducted 

 and four treatments are now being subjected to a service test. Work 

 has also been done with the object of simplifying the preparation 

 and application of cuprammonium solution to fabrics to such an 

 extent that this might be done on the farm, since the cuprammonium 

 treatment gives greater mildew resistance than any other treatment 

 known at the present time. Tests have been made on the water- 

 proofing qualities of various materials, including complex compounds 

 made from turpentine. Investigations are in progress for the pur- 

 pose of increasing the life of tobacco shade cloth, which it is estimated 

 costs the tobacco growers $3,000,000 annually. It is hoped to doul)le 

 the life of the cloth. 



MANUFACTURE OF INSECTICmES. 



Work is in progress to determine cheap and effective methods of 

 preparing insecticides and fungicides on a commercial scale, in addi- 

 tion to the chemical investigations on insecticides elsewhere reported. 

 New, efficient, and cheaper insecticides must be found if agricultural 

 workers are to combat successfully or finally exterminate some of the 

 pests most destructive to farm crops. This work includes studies of 

 the properties of commercial insecticides, and during the year 

 progress was made in determining the rate of deterioration in cer- 

 tain materials. 



The investigation to determine the rate of deterioration of lileach- 

 ing powder shows that the rate of deterioration depends mainly upon 



