THE MICROSCOPE. 105 



Glucina leaves large stars when a drop of a four-per-cent. solu- 

 tion of the glucium sulphate is evaporated on a slide. 



Boracic acid, after evaporation of a two-per-cent. solution, gives 

 a series of very small plates, hardly two mm. in diameter, which do 

 not show any cross when magnified over eighty times. 



The alkalies possess marked optic properties. Four-per-cent. 

 solutions were made soluble in water, the sulphates being employed. 



Potassium sulphate gives, at o° of the nicol, a series of rhombic 

 plates, not well defined; at 90° blue virus, with yellow or red spots, 

 developed. These cannot be taken for any other alkali. 



Sodium sulphate appears dull and silvery white, in hopper- 

 shaped quadratic crystals. 



A large number of other sulphates are given in the article, with 

 characteristics of each. The above will give an idea of the nature 

 of the work. 



The Preparation of Marine Algce. — The conclusion reached is 

 that solutions of osmic acid and corrosive sublimate in sea-water 

 gave good preparations, but the iodine solution was regarded as the 

 best reagent. 



A few drops of a saturated alcoholic solution of iodine, added 

 to the sea-water, gives the desired results. The algae remain in the 

 solution y>2 — 1 minute, and are then transferred directly into 50 per 

 cent, alcohol. 



Double-staining Nucleated Blood-Corpuscles,' with Anilin Dyes. — 

 The successful combinations used are the following: Rosein and 

 anilin green; fuchsin and methylen blue; fuchsin and Bismarck 

 brown; eosin and vesuvin; iodine green and Bismarck brown; Hoff- 

 man's violet and Bismarck brown; anilin violet and methylen blue. 

 The green dyes were not permanent. The solutions used should be 

 fresh. 



Cobweb Micrometers. — This form of micrometer is preferred, 

 which has both webs movable, instead of one being fixed as is usual. 

 This saves time and promotes accuracy. 



A New Form of Gastroscope. — An instrument for inspecting the 

 interior parts of the body, as the larynx, oesophagus, stomach, intes- 

 tines, bladder, etc. A small electric light is introduced into the 

 cavity, and streams of water prevent any inconvenience from heat. 

 The instrument can be introduced into the bottom of the stomach 

 without difficultv. 



