1194 Journal of Applied Microscopy 



carbonate, carefully added. The turbid liquid is then either filtered, or, what is 

 better, whirled in the centrifuge. The clear liquor is evaporated to dryness, the 

 ammonium salts driven off and the residue extracted with alcohol or amyl alcohol. 



Or, in the absence of sulphates, another method is open which avoids the 

 \ise of alcohol. Treat the aqueous solution with ammonium hydroxide and 

 ammonium oxalate, then add sufficient ammonium carbonate to precipitate the 

 magnesium ; separate the precipitate by filtration or by means of the centrifuge. 

 Evaporate the clear liquid and ignite the residue. Treat with HCl, evaporate 

 to dryness, and test the residue as given below. This method is open to a 

 number of objections and is somewhat limited in its application. 



Test a portion of the material with potassium chlorplatinate or ammonium 

 silicomolybdate for Rb and Cs. 



Another portion is treated with platinum chloride for K. 



Sodium is tested for with uranyl acetate or, if thought to be in only small 

 amount, with uranyl acetate and magnesium acetate. If much K has previously 

 been found, either separate this element by the perchloric acid method, or test 

 for Na at once with potassium antimonate or bismuth sulphate. 



There now remains Li to be searched for. This can be done by any one of 

 the three methods mentioned under the head of this element. 

 Cornell University, Chemical Laboratory. E. M. ChamoT. 



Staining Sections for Class Work. 



Being under the necessity of staining large numbers of sections of tissues 

 sectioned in both paraffin and in celloidin, for class work, we have adopted the 

 following methods for shortening the time and facilitating the technique. 



The paraffin sections being mounted on cover-slips, and the paraffin removed 

 by the usual method, they are placed in rows on a corrugated glass disc of a 

 staining dish, the disc being provided with handles of wire, and resting in a 

 dish of xylol deep enough to cover the sections. Upon this disc or tray the 

 sections can be quickly transferred from one reagent to another, if necessary, 

 allowing the disc to drain upon pieces of filter paper between the different 

 reagents. In this way thirty or thirty-five sections can be stained in a very few 

 minutes on one staining disc. 



For celloidin sections, the reagents being in small, deep dishes, the sections 

 are placed on a piece of copper or brass wire gauze, folded into the form of a 

 cup, and resting in a dish of alcohol or water. By means of this porous cup the 

 sections can be quickly transferred from one dish of reagent to another and 

 easily drained ; the number of sections that can be stained at once being 

 indefinitely large. Newton Evans, M. D. 



American Medical Missionary College. 



