Journal of Applied Microscopy. 



121 



more, it was found that the distinction 

 between these two powders could be 

 made more apparent by the application 

 of a solution of ammonium hydrate. Un- 

 der the influence of this liquid rhubarb 

 turns a dark brick-red color, canaigre 

 with the same reagent gives a brownish 

 color. To apply the test, carefully place 

 on a glass surface a small amount 

 of the powder and moisten it with 

 a drop or two of ordinary ammonia 

 water. At once the color reaction 

 becomes apparent. 



Fig. 4. 



Several interesting points have been 

 derived from the examination of pow- 

 dered senna. It would be impossible in 

 the space devoted to this article to enter 

 upon this subject in detail, but by re- 

 ferring to the "Journal of Pharmacy," 

 Nov. 1896, pages 585 to 588, and June, 

 1897, pages 298 to 307, the result of this 

 investigation can be seen. One point of 

 interest in connection with this study, 

 that may be mentioned here, is the 

 method found sufficient for the detection 

 of a possible adulterant, chestnut 

 leaves. The latter can be revealed under 

 the lens by the presence of tracheids 

 and pitted cells which compose the mid- 

 rib of the chestnut leaf and also by the 

 rapidity with which the tannin of the 

 latter leaf reacts by the addition of a 

 drop of a solution of ferric chloride. The 

 directions for the detection of chestnut 

 leaves by this method are as follows: 

 Place half a gram of the number 60 pow- 

 der in a layer of uniform thickness on a 

 clean glass slide and place this on a 

 piece of clean paper. Drop upon this one 

 drop of a five per cent, solution of fer- 

 ric chloride. The drop remains for some 

 time in the form of a globule un- 

 absorbed. If senna alone be present the 

 powder as seen through the drop re- 

 mains comparatively unchanged; if any 

 chestnut leaves be present they will be 

 shown by the particles under the drop 

 in less than thirty seconds, turning a 

 dark blue or black color in the presence 



of tannin. A very small percentage of 

 chestnut leaves in senna can thus be 

 detected. 



L. E. Satre. 



School of Pharmacy, University of 

 Kansas, June 25, '98. 



Laboratory Tables. 



During a recent tour of mspection to 

 many of the biological laboratories of 

 the eastern section of the United States, 

 in search of information regarding lab- 

 oratory construction and equipment, a 

 question which was almost invariably 

 asked me at each place visited was, 

 "What sort of laboratory table do you 

 use?" No one seemed to be satisfied 

 with his own kind, but wanted some- 

 thing different. While the size of the 

 top, the height from the floor, the posi- 

 tion of the drawers, etc., all seemed to 

 be important details, the matter which 

 was most inquired about was the pre- 

 paration of the top so that it would 

 stand the rough usage to which a lab- 

 oratory table is necessarily subjected. 

 The experience with the tables in the 

 biological laboratories in this institution 

 has been so satisfactory that it is 

 thought possible that a description of 

 the manner in which the tops were 

 treated may be of assistance to other 

 instructors. When the laboratories were 

 opened here, eight years ago, tables for 

 the accommodation of thirty students 

 were constructed. The legs and sides 

 were first oiled so as to prevent drops of 

 the stain applied to the top from making 

 spots upon other parts upon which it 

 might be spattered. The freshly planed 

 soft wood tops, free from spots of 

 grease, were covered with a solution 

 made by boiling logwood chips in an 

 iron kettle. No definite proportion of 

 chips and water was used, but a fairly 

 strong solution was made. This was 

 generously applied with a brush or swab 

 and allowed to dry thoroughly. A sec- 

 ond coat was applied in the same way 

 and dried. Then a strong solution of 

 copperas in hot water followed. When 

 dry, the table top was well rubbed with 

 sandpaper, and hot paraflSn of high 

 melting point (55° to 60° C.) poured on. 

 By means of a hot flat-iron the paraffin 

 was thoroughly rubbed into the wood, 

 thus fllling all the pores and coating the 

 surface. When cool, the superfluous 

 paraffin was removed by scraping the 

 surface with a thin piece of steel (back 

 of saw-blade) having a smooth, straight 

 edge. The tops were then ready for use. 

 The tables in these laboratories have 

 been in use for eight years by a number 

 of students varying each year from one 

 hundred to one hundred fifty, and have 



