566 Chronicles of Science. [Oct., 



a screw cut inside into "which a cork m is screwed to receive a 

 needle n, to which a hair is fastened by wrapping gum paper 

 around. Turning the cork facilitates the adjustment of the hair to 

 the proper inclination. A slight pressure on the button l brings 

 down the hair, and the spring inside of f instantly lifts it again 

 when the pressure is removed. The tube r turns in the clamp d in 

 order to adjust the hair and cork more conveniently, and when 

 brought back again it is tightened by a set screw. Complicated as 

 it may appear, only one movement is added to the microscope stand 

 by this instrument, the one, namely, which gives the vertical motion. 

 When the apparatus is to be used, the material to select from is 

 placed on the sub-stage c and focussed, then the point of the hair is 

 approximately brought over the selected object by means of the 

 stage movements and turning of d ; this brings the hair nearly in 

 focus too, because it is almost in the same plane with the object. 

 Next adjust the hair precisely over the selected shell, press down 

 the button l, and the shell will adhere to the hair. Now remove 

 the slide with the material and substitute a glass slide moistened by 

 breathing on it, and having brought it in proper position briskly 

 dip down the button l again and the shell will be deposited on the 

 glass slide. If the mechanical stage has a graduated indicator, the 

 finger may be moved along regularly and shells may be placed at 

 equal distances in lines. After the cover glass is carefully placed 

 over it, Canada balsam may be run in by capillary attraction with- 

 out disturbing the position of the shells. 



Heat. — Dr. J. D. Boeke, Teacher of Chemistry at the Hoogere, 

 Burgerschool at Alkmaar, opposes the statement of Mr. Loew that 

 ozone is formed by rapid combustion. On repeating Mr. Loew's 

 experiment with this slight modification, that a stream of oxygen 

 instead of air was blown through the luminous flame of a Bunsen's 

 burner into the mouth of a glass balloon, he really found that the 

 air in the balloon had assumed a peculiar odour, and the property 

 of colouring blue a mixture of starch paste and of potassium. But 

 it appears that both changes are the result of the formation of a 

 compound of oxygen and nitrogen (probably dinitric trioxide or 

 nitric dioxide), not from the formation of ozone, as Mr. Loew asserts. 

 So when Mr. Loew declares that he was able to " identify the for- 

 mation of ozone by its intense odour and the common tests," he was 

 somewhat rash in this conclusion. Still Mr. Loew's experiment is 

 a very interesting and easy one, and will soon take its due place in 

 the series of lecture-experiments intended to elucidate the complex 

 phenomena of combustion. 



H. Sainte Clair e-Deville relates at great length a series of ex- 

 periments which may be summarized as follows : — Perfectly pure 

 iron kept at temperatures varying from 150°-1600°, is treated with 



