472 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



gen derivatives of fluorescein and the inorganic halides; (2) the de- 

 termination of minute amounts of arsenic in products like coal-tar 

 colors; (3) the separation and identification of mixtures of colors 

 permitted by Food Inspection Decision No. 76. 



In connection with the drug work of this laboratory an interesting 

 study has been made of a method for the determination of benzalde- 

 hyde, cinnamic aldehj^de, and vanillin, based on the fact that these 

 aldehydes form insoluble semicarbazones with semicarbazids. The 

 advantages of this method are: (1) Ease of manipulation; (2) dry- 

 ing at 100° C, where the phenylhydrozone methods necessitate a 

 lower temperature; (3) the resulting semicarbazone is crystalline in 

 character, of a definite melting point, and affords a ready method of 

 identification of the aldeln^de under examination; (4) accuracy, the 

 duplicates varying within 0.5 per cent. 



Other drug investigations included a study of Haarlem oil and 

 one of copaiba. From examinations of the Haarlem oils generally 

 recognized as genuine, this product appears to be obtained by boiling 

 together a fatty oil, sulphur, and turpentine for a considerable time 

 (sixteen to twenty-four hours). The oil so obtained is viscous, brown- 

 ish in color, and possesses the characteristic turpentine-sulphur odor. 

 The volatile oil is yellow in color and leaves a residue of not more 

 than 15 per cent insoluble in concentrated sulphuric acid. 



Experiments made in this laboratory, in which linseed, olive, and 

 castor oil were boiled with sulphur and turpentine for sixteen hours 

 at the boiling point of turpentine, indicate that the nature of the 

 fatty oil has little influence on the properties of the final product. 

 In all cases the volatile oil was yellow in color, contained sulphur, 

 and resembled that obtained from the imported oils in all particulars. 

 No amber oil, tar oil, aloes, etc., were found in any of the imported 

 oils, the yellow color of the volatile oil being due to the combination 

 of sulphur with the turpentine. 



A continuation of the study of copaiba shows that the South 

 American products as a rule are dextro-rotatory. This is due to the 

 resin present, w^hich is dextro-rotatory, and since its specific rota- 

 tion is about -(-78^ in alcohol, while that of the oil is —7° to —35°, 

 the balsam, due to the percentage of resin, is dextro. In the case of 

 African balsam, the original balsam is laevo, the resin Isevo, and the 

 oil dextro. Gurjun balsam follows copaiba in its rotation. 



The chemists of the laboratory have also done collaborative work 

 on methods of analysis of paprika, preservatives, flavoring extracts, 

 colors, chocolate and cocoa, coffee, sugar, drugs, and medicines. 



OMAHA LABORATORY. 



Three hundred and forty-nine interstate inspection samples were 

 examined at the Omaha laboratory, about one-third of which were 

 found to be adulterated or misbrancled, and 100 miscellaneous samples 

 were received, coming principally from the Treasury Department 

 (internal revenue) and the War Department (office of purchasing 

 commissary). As the chief of the laboratory was detailed to Chicago 

 for over three months, the output of work was materially reduced. 

 Coffees and cocoas, flavoring extracts, fruit and saccharine products, 

 and spices and condiments constituted the largest classes of products 

 examined. Nearly half of the spices and 10 out of 14 cereal products 



