BEPOET OF THE SECRETARY. 83 



ance of this work is of fundamental importance, and much time is 

 devoted to researches of this kind, about 600 determinations having 

 been made to this end during the year. 



CONSERVATION OF TURPENTINE, ROSIN, ETC. 



The work which has been in progress for several years on wood 

 turpentine and other products obtained in the distillation of wood 

 has been so far advanced that its publication is deemed advisable. 

 This work shows how the number and value of the products ob- 

 tained in the distillation of wood can be increased, how the quality 

 of the products may be improved, and the cost of the products de- 

 creased. Properly refined wood turpentine has been found to be a 

 suitable paint and varnish thinner for all but the highest grade 

 varnishes, and it may safely be used by the workman in well-ven- 

 tilated places. 



The work on the misgrading of rosin has developed the fact that 

 such misgrading is largely due to the practice of cutting the samples 

 on which the rosin is graded too large, and also to the fact that the 

 standard type sample^s with which the rosin to be graded is com- 

 pared rapidly bleach out and become lighter in color under the 

 severe climatic conditions existing in the South. The indications 

 are that in the neighborhood of 400,000 barrels of rosin are annually 

 misgraded from the above-mentioned causes, and the loss occasioned 

 by such misgrading is chiefly at the expense of the rosin producer. 

 In order to prevent this as far as possible, a simple device has been 

 prepared with which the producer of rosin can himself accurately 

 grade his product and in this way check the subsequent official 

 grading. 



EXAMINATION OF CONTRACT SUPPLIES. 



The testing of deliveries to the various Government departments 

 of paper, textiles, leather, turpentine, rosin, and other materials has 

 steadily increased, thus showing a gratifying appreciation of the 

 help which the Bureau of Chemistry can render the other depart- 

 ments. Frequent calls for advice in the purchase of the above-men- 

 tioned materials and for service on inspection committees are re- 

 ceived, and the assistance which has been rendered in the preparation 

 of specifications and in the testing of supplies has saved thousands 

 of dollars annually to the Government. These specific materials are 

 examined in the Leather and Paper Laboratory, all other contract 

 supplies being examined in the Contracts Laboratory, devoted exclu- 

 sively to such work. A total of 2,309 samples were examined in the 

 Contracts Laboratory last year. Of these over 1,300 were colors, 



