224 MICROSCOPICAL TECHNIQUE. 



the amount of water added, Knaikl of gypsum may be formed 

 with a corroded core of anhydrite. Although anhydrite has been 

 frequently produced artificially, none of the methods heretofore 

 used have simulated its production in nature from the evaporation 

 of sea-water. 



An Excellent Etching Fluid for Glass has recently been pub- 

 lished in the Central Zeitung fur Optiker unci Mechaniker^ xii., p. 57. 

 It consists of. two solutions which are to be kept in separate vials, 

 and prepared according to the following directions : — 

 No. I. — Dissolve sodium fluorite ... 36 grams. 



in distilled water .,. ... 500 cubic centimeters. 



and add potassium sulphate ... 7 grams. 

 No. 2. — Dissolve zinc chloride ... 14 grams. 



in distilled water ... ... 500 cubic centimeters. 



and add cone, hydrochloric acid 65 grams. 

 These solutions can be kept in ordinary glass vessels, hence no 

 gutta percha bottles are necessary. When wanted for use equal 

 volumes are mixed in a suitable vessel, best in a hollow paraffin 

 cube, which is easily made by cutting a hole in a piece of paraffin 

 with a knife. A small quantity of Indian ink is recommended as 

 an addition in order to enable the writer to see what he has 

 written. This fluid is said to be superior to the more difficult 

 preparations, and it is said that the finest hair lines have been 

 etched on glass with this medium. — Meyer's Druggist. 



Bacteriological Examination of Blood and Tissues.— Inghilleri^ 

 gives a new rapid double staining method for bacteriological 

 examination of the blood and other tissues, including the study of 

 phagocytosis and parasites of malaria, which he claims to excel, 

 not only in quickness but in precision. A cover glass preparation 

 (by the usual methods), or a section prepared from the tissues, is 

 placed in chloroform for thirty minutes, and afterwards stained in 

 the following fluid : — i per cent, solution of eosin in 70 per cent, 

 alcohol, 40 parts ; saturated aqueous solution of methylene blue, 

 60 parts, the specimen being gently warmed in this fluid for two or 



* Central b. fur. Bakteriol.^ May, 1894, in Btit. Med. fourn., June 21, 

 1894, Epit., p. 13. 



