ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
237 
(6) Miscellaneous. 
Laboratory Dish.* — Prof. W. M. L. Coplin describes the dish used 
in his laboratory in the manipulation of paraffin sections. As the illus- 
tration (fig. 37) shows, the vessel is made of glass; it has the following 
measurements : 3J in. high, 1 in. square at bottom, If in. square three 
Fig. 37. 
inches from bottom, If in. in diameter at top, which is round and covered 
with'an air-tight cover; the base is nearly 2 J in. in diameter. The inside 
is ridged on two opposite sides (fig. 38), so that five grooves are formed 
in which eight slides may be packed, three pairs back to back and one 
at each end. 
Micro-Sclerometer for Determining the Hardness of Minerals.f — 
Mr. T. A. Jaggar, jun. (Camb. Mass.) describes an instrument which 
appears to give a new and valuable method of determining the hardness 
of minerals, whether simple, compound, amorphous, or crystalline. The 
quality which it is proposed to measure is the resistance offered by a 
body to the removal of particles of its substance by a defined diamond 
point moving in contact with it under uniform conditions. The instru- 
ment is applied to the Microscope, so that it may be used for either thin 
sections or crystal faces. The adjustments of the instrument are such 
that any of the variable elements in the process of abrasion may be made 
functional while the others are maintained constant. The principle is 
as follows : — A diamond point of constant dimensions is rotated on an 
oriented mineral section under uniform rate of rotation, and uniform 
weight to a uniform depth. The number of rotations of the point, a 
measure of the duration of the abrasion, varies as the resistance of the 
* Journ. New York Micr. Soc., xiii. (1897) pp. 87-9 (2 figs.). 
t Arner. Journ. Sci., Dec. 1897, pp. 399-112 (1 pi. and 2 tigs.). 
