6o THE MICROSCOPE. 



drons ; and if from common jioultry they will be cubes more or less 

 perfect. There would seem to be room for more acurate research 

 in this direction. — [We should say so. — Ed. Bistoury.] [We should 

 say so twice. — En. The Microscope.] 



In liquids small particles often show dancing motions under the 

 microscope, and similiar motions have been attributed to dust par- 

 ticles in air, and accounted for by the shock of molecules with the 

 particles. In a recent paper treating fully of the movements of very 

 minute bodies, Herr Niigeli calculates from data of the mechanical 

 theory of gases as to the weight and number and collisions of mole- 

 cules, the velocity of the smallest fungus particles in the air that can 

 be perceived with the best microscopes, supposing a nitrogen or 

 oxygen molecule to drive against them. It is, at the most, as much 

 as the velocity of the hour-hand of a watch, since these fungi are 

 300 million times heavier than a nitrogen molecule. The ordinary 

 motes would move 50 million times slower than the hour-hand of a 

 watch. Numbers of the same magnitude are obtained for move- 

 ments of small particles in liquids. In both cases a summation of 

 the shocks of different molecules is not admissable, as the move- 

 ments are equably distributed in all directions. Herr Nageli there- 

 fore disputes the dancing motion of solar dust particles, and attrib- 

 utes the Brownian molecular motion to forces active between the 

 surface molecules of the liquid and the small particles; but he does 

 not say how he conceives of this action. — Stoddart's Review. 



Last evening, at the Conversazione of the Chemical Society, I 

 showed how easily the adulteration of sugar by starch-glucose, can 

 be detected by the microscope. 



I had two samples of coffee sugar, one being a pretty high 

 grade sugar, and the other being of as low a grade as there is in the 

 market; I had, besides, a sample of the starch-sugar in small grains, 

 which is used to aduterate sugar, and also a sample of adulterated 

 sugar, "new process sugar," so-called. 



Both the samples of coffee sugar, when seen by reflected light 

 through an A eye-piece and a 3*^- objective present a beautiful ap- 

 pearance. Every crystal is perfectly formed and thoroughly 

 transparent. A group of these crystals looks like a mass of rock 

 candv. 



