REPORT OF NATIONAL MUSEUM, 1922. 101 



whooping cough, typhoid fever, and hydrophobia by serums and vac- 

 cines and how diagnostic skin tests are made are an addition to the 

 series of public health collections. Fifteen colored transparencies 

 were mounted during the year at the end of the gallery, where use can 

 be made of the natural light. These transparencies show important 

 steps in the preparation of vaccines and serums by methods ap- 

 proved by the Government. Two large photographs show a modern 

 plant in which these medicinal agents are prepared for distribution. 

 The installation of six new exhibits was completed in the section of 

 wood technology during the past year. These comprise an exhibit of 

 balsa, a wood weighing but little more than half as much as cork, 

 consisting of a cross section of young balsa tree, a squared small 

 beam 4 feet long, and an ice-cream box constructed entirely of this 

 wood, the insulating value of which is such that a quart of ice cream 

 will remain firm in this box for five hours with an atmospheric 

 temperature of 75° ; specimens showing the work done by the Linder- 

 man automatic dovetail glue jointer in jointing small waste pieces 

 and building up wide lumber from narrow stock; the exhibit of the 

 Hammermill Paper Co. illustrating the manufacture of sulphite 

 wood pulp and paper and arranged in tw T o series to show steps in 

 the process used and the quantity of each material required for 100 

 pounds of paper; an airplane propeller of American walnut to 

 replace the white-oak propeller transferred to the aircraft building; 

 a series of containers and molded articles made of wood pulp by 

 the Drake process; and the series of specimens illustrating uses of 

 American walnut contributed by the American Walnut Manufac- 

 turers' Association and some of its member firms. The walnut series 

 includes veneer cutting and beautifully figured veneered panels, gun 

 stocks, an automobile steering wheel, and specimens of parquetry 

 flooring. 



PRESENT CONDITION OF THE COLLECTIONS. 



With the exception of slight fading of certain textile fabrics which 

 are affected by the light and the discoloration of certain food samples 

 due to exposure to light and heat, there has been but very little 

 deterioration of either the exhibit or study materials. 



The older material in the division of medicine has been carefully 

 examined and only expected deterioration is noticeable. Some of 

 the old series of chemical drugs, particularly those which are subject 

 to efflorescence and deliquescence, are worthless, and some of the 

 pharmaceutical preparations made years ago which undergo changes 

 are no longer fit for exhibition purposes and have been removed to 

 the storage room until they can be examined by a condemnation com- 

 mittee. The preserving fluid on the fresh anatomical specimens was 

 changed during the year. 



