484 MANIPULATION. 



able observations will be lost if the labour of packing and un- 

 packing the instrument and apparatus have to be frequently 

 repeated. A glass shade, especially a stout one of the old 

 make, with a knob at the top, will be found to keep off the 

 dust as effectually as any well-constructed box or case. 

 Drawers and cupboards, for containing preparations in bottles 

 and boxes, will be found very convenient. A small nest of 

 drawers, fitted up under the table, will be useful for keeping 

 thin glass covers, spare slides, cutting instruments, &c. In 

 the winter, when fires are in use, it will be necessary to cover 

 over any preparations that are about to be dried before being 

 mounted, as minute particles of carbon are continually being 

 deposited in aU situations; for this purpose small shades, such 

 as are employed for raising young plants, wiU be found par- 

 ticularly convenient. 



To Clean the Optical Part of the Microscope. — In order to 

 clean the glasses of the eye-piece, they should be unscrewed, 

 and wiped either with a piece of clean lawn or wash leather ; 

 an old soft cambric handkerchief wUl be an excellent substi- 

 tute for either. In the case of the object-glasses, the wiping 

 should be conducted with great care; in the majority of 

 instances, a camel's-hair pencil will remove any dust, but for 

 all other purposes the leather or linen wiU be required. Some 

 persons recommend that the wash-leather should be impreg- 

 nated with putty or crocus powder; both this and the linen 

 should be kept perfectly free from dust, in a box, and em- 

 ployed for no other purpose. 



Glass Slides may be freed from all grease by washing them 

 with potash; the Rev. J. B. Eeade has recommended an 

 infusion of nut-galls (which contains a quantity of tannic 

 acid) for the same purpose. In wiping the slides and the 

 covers as well, be careful not to employ a substance likely to 

 leave any nap or down behind, as coloured filaments, derived 

 from table-covers, pocket-handkerchiefs, &c., have more than 

 once been mistaken for highly organized structures. 



Cabinets and Boxes for holding Microscopic Objects. — The 

 slides generally employed by microscopists are one of the 

 sizes recommended by the Microscopical Society, viz., three 



