286 



CONTKIBUTIONS TO MICRO-MINERALOGY. 



be rotated to two persons on each s'ldv. of the demonstrator 

 after he has arranged the object, and thns be examined by five 

 persons in succession. This has the advantage of economy over 

 Nachet's three and four bodied microscopes (see vol. ii., page 72), 

 even if some of its other points are not attained. 



Rc-ngi>ut Bottu-ii. — In vol. ii., page 58, of this Journal, my 

 friend Dr. Beale described and figured a Re-agent Drop- 

 bottle used by him, and an improvement on its form by myself. 



Fig. C. 



Finding that many persons meet with a diffi- 

 culty in filling them by the plan there recom- 

 mended, though it is a very simple operation, 

 and moreover, that certain re-agents are 

 decomposed when they enter the heated 

 bottle, 1 have again improved iis construc- 

 tion, which will be readily understood by 

 fig. 6. Instead of drawing out the neck of 

 the bottle to a capillary-tube, a piece of 

 thermometer-tube is drawn out to a fine 

 point, and is then ground into the neck of 

 the bottle like a stopper ; on the outside 

 of the neck a glass cap is ground in the same 

 way as in a spirit-lamp. When the bottle 

 has to be filled, the drop-tube stopper is 

 removed, and firmly replaced after the bottle 

 is about two thirds full, the warmth of the 

 hand affecting the contained air that rises to 

 the end of the bottle when the drop-tube is 

 pointed downwards on a slide, forces the liquor through the 

 thermometer-tube stopper drop by drop ; and this is more 

 satisfactorily eftected, as the bore is of one diameter along its 

 whole length, instead of being an elongated cone as in the old 

 form. There should be a sufficient quantity of these in a 

 proper case; such, with the other instruments here described, 

 may be obtained of Messrs. Murray and Heath, opticians, of 

 43 Piccadilly, ^^'alch-glasses, excavated and plain slides, stir- 

 rers, a Smee's battery for electro-chemical decompositions, and 

 a Groves' baltery for examining the ellects of electro-magnetic 

 cinrents on crystallization, &c., will com])lete the micro-mineralo- 

 gical laboratory, which may equal, if not rival, Wollaston's 

 laboratory that was contained in a tea-tray. 



