1893.] MIOKOSCOPICAL JOURNAL. 103 



will be published from time to time showing the latest dis- 

 coveries in this direction. 



In the prosecution of experiments upon the oils, butter, and 

 other fats, a new device connected with the microscope has been 

 invented during this year, which promises to be of great value 

 in the detection of adulterations of food fats and medicinal oils, 

 such as have hitherto escaped detection. 



New and important experiments have also been made in con- 

 nection with silver nitrate as a test for adulterated food, medici- 

 nal or other oils, such as cotton-seed, olive, castor, linseed, etc., 

 with well-defined results, which will be illustrated in the forth- 

 coming report, showing the relative reactions of the silver nitrate 

 and the respective oils. Further experiments are also in 

 progress relating to the testing of farmer's binding twine, pure 

 and adulterated. Samples of cotton for microscopical examina- 

 tions have been received from nearly every cotton-growing 

 countrv in the world, as also a large assortment of animal fibres 

 for examination and comparison. 



A Cement which Promises to be of Value in Micros- 

 copy. — It has long been known that glycerin and litharge make 

 an excellent cement for many purposes, and the writer suggested 

 its use in microscopy in the National Druggist as far back as 

 18S4. Some months ago he had occasion to build some deep cells 

 for opaque objects, and used the lead cement for the purpose. Up 

 to the present time the cells seem to be all that could be wished. 

 The following is the method of preparing the cement : Take any 

 convenient quantity of litharge and reduce it to an impalpable 

 powder by porphyrization. Place the powder in a crucible and 

 expose to a bright red heat for some time. Keep this powder in 

 closely-stoppered vessels. When needed for use mix with suffi- 

 cient anhydrous glycerin to make a paste, and with the paste 

 quickly form your cells by the aid of a penknife and the turn-table, 

 using the latter as a jDOtter's wheel is used, forming up the sides 

 of the cell by gentle pressure from the knife-blade. This cement 

 hardens very rapidlv, resists almost all fluids, even mineral acids, 

 and does not shrink appreciably in drying. It is not affected by 

 any degree of heat short of the boiling-point of glycerin. It ad- 

 heres most firmly to any surface to which it may be applied, and 

 can thus be used for cementing almost all kinds of substances — 

 metal, porcelain, glass, etc. Only a small amount of the litharge 

 and glycerin should be mixed at a time. — National Druggist. 



To Fix Paper on Glass or Metal. — The Reimc Phoio- 

 graphiquc gives the following, which is said to be excellent : Mix 

 30 gm. tragacanth and 120 gm. gum arabic, and dissolve in 500 

 gm. distilled water. Filter and add 2.5 thymol dissolved in 120 

 cem. glycerin. 



