1893.] MICROSCOPICAL JOURNAL. 103 



will he published from time to time sliowinj^ the latest dis- 

 coveries in this liiiection. 



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

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

 invented durinjj this year, which promises to be of <5reat 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 lest for adulterated food, medici- 

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

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

 coming report, showinsj^ the relative reactions of the silver nitrate 

 antl the respective oils. Further experiments are also in 

 proijress 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 

 country 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 glvcerin and litharge make 

 an excellent cement for many purposes, and the writer suggested 

 its use in microscopy in the National Dr7iggist as far back as 

 1SS4. Some months ago he had occasion to build some deep cells 

 for opaque objects, and used the lead cement for the purpose. L^p 

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

 The following is the mcthotl of preparing the cement: Take anv 

 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 anhvdrous 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 potter'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 appreciablv in drving. It is not affected by 

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

 heres most Hrmlv to anv sinface to which it mav be applied, and 

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

 metal, porcelain, glass, etc. Only a small amountofthe litharge 

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



To Fix Paper on Glass or Metal. — The Rc>'uc Photo- 

 grapJiiquc gives the following, which is said to be excellent : Alix 

 30 gm. tragacanth and 120 gm. gum arable, and dissolve in ^00 

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

 cem. irlvcerin. 



