BUREAU OF CHEMISTRY. 575 



SPECIAL INVESTIGATIONS. 



MoRPniN. — Considerable work has been done with a \ieyv of devis- 

 ing: methods for the determination of morphin (generally. The re- 

 sults of this investifration have been encoiira^^inji:. Some new facts 

 have been brou<;ht to lijiht which have led to the development of sim- 

 ple, rapid, and accurate methods for opium, opium preparations, mor- 

 phin tablets, and the simpler liquid mixtures containing morphin. 

 Further work is being pursued looking toward the application of 

 these methods to sirups and the more complex liquid mixtures. In 

 case of liquids containing glycerin promising results have already 

 been obtained. 



In this connection the United States Pharmacopoeia method has 

 been studied, with the result that its chief source of error has been 

 definitely traced and a good idea obtained of the magnitude of the 

 error. 



Chloroform. — In order to obtain methods for the determination of 

 small amounts of chloroform in medicinal products, a broad study 

 has been made of the reaction velocity between alcoholic pota&sium 

 hydroxid and chloroform. The information thus gathered has been 

 made use of in routine analyses. 



During the last fiscal year investigation has been made for the pur- 

 pose of securing a method for the determination of nitroglycerin 

 in medicinal tahlets. Two methods found in the literature have 

 been successfully adapted to the purpose. Much work based on these 

 methods has been done by various analysts in the division of drugs 

 and the methods have now been made the subject of cooperative work 

 by the Association of Official Agricultural Chemists for the purpose 

 of further testing and, if possible, improving them. 



Investigations have been continued upon the keeping qualities of 

 liquid pepsin preparations and to the ricin method of assaying pep- 

 sin and testing for small quantities of it in the presence of other 

 substances. Some commercial preparations while retaining nearly 

 their full activity in cold storage lose much of their proteolytic 

 power when stored at room temperature; others are fairly stable even 

 at room temperature. The Jacoby-Solm modification of the ricin 

 assay has been specially studied, and as further modified in this 

 bureau it has been satisfactorily used for tlie detection of pepsin in 

 chewing gum and in assaying galenicals for pepsin. The method is 

 now being tried out by cooperating chemists throughout the United 

 States, and it wjll later be submitted to the Association of Official 

 Agricultural Chemists for their consideration. 



Washington Food Inspection Laboratory. 



The work of the Washington food inspection laboratory during 

 the past year has changed to a certain extent, more than ever turning 

 toward tlie executive work in connection with the enforcement of the 

 food and drugs act. In fact, at the present time the chief work of 

 this laboratory is the consideration of reports made by the branch 

 laboratories on food products. This work is divided into two parts: 



First, interslale casos: All of the analytical reports made by the 

 branch laboratories on food products, with the exception of those 



