738 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



block. These squares or circles of cardboard may be made of board of 

 several thicknesses, varying from one to several millimetres, so that in 

 selecting a protector the thickness may be adapted to the height of the 

 filaments of the fungus. This method of mounting has proved very 

 convenient for specimens of Stilbum, Grophium, Ceratostomella, and other 

 fungi. It is advisable to poison the specimen after mounting by spray- 

 ing it with a strychnin solution. 



(6) Miscellaneous. 



Immersion Oil Bottle.* — Watson and Sons claim that this form of 

 oil bottle (fig. 86), which is constructed on the lines of the unspillable 

 inkpot, possesses the advantage of its prototype, 

 and is also very clean. The cover is made of 

 boxwood, and from its middle a wooden rod for 

 obtaining a drop of oil passes down to near the 

 bottom of the tube. 



Watson's "Facile" Turntable with Ball- 

 bearing.! — In this new turntable (tig. 87) the 

 rotating table is below the level of the supporting 

 block, which is higher than in ordinary models. 

 The centre pin is of hardened steel, and the table 

 at the centre where the pin comes in contact, is 

 fitted with a hardened steel ball. As the pin 

 and ball only engage at a small point, the action 

 is so free that a slight push will make the table 

 rotate for a considerable time. On the surface of the table is engraved 

 a ring of such diameter that when a 3 in. by 1 in. slide is central on 

 the table, the four corners exactlv touch the circumference of the circle. 



Fig. 87. 



Microchemical Test for Zinc.J — H. C. Bradley states that when a 

 moderately concentrated solution of a zinc salt is treated with sodium 

 nitro-prusside, there is thrown down a salmon-pink precipitate of zinc 

 nitro-prusside, the characteristic feature of which is its definite and 

 readily identified crystal form. All other nitro-prussides of the heavy 

 metals which are insoluble in water are amorphous, slimy precipitates 

 resembling the ferro-cyanides in general physical properties. Though 

 the reaction is not new, its possibilities as a reliable test for zinc appear 



* Watson and Sons' Catalogue, 1906, p. 104. + Special Catalogue, p. 10. 



% American Jouin. Sci., xxii. (1906) pp. 327-8. 



