WATEK-BATH SPRING-PRESSES 45 3 



It is also needful to Have a smaller plate, much thinner, of brass, 

 having a groove cut in it into which the ordinary 3x1 in. mounting 

 slip can easily slide, but so grooved as to leave a space between a 

 ledge on each side on which the slip rests, and the main surface of 

 the brass under the slip. In this way there is always a film of 

 heated air between the main surface of the heated brass and that of 

 the glass, giving more facility for rapid and delicate heating. This 

 may be either a separate ' table ' or a plate fitted to a retort-stand. 



Beyond this, however, heat of various kinds, dry and moist, of 

 variable but determinate temperatures, w^ill be required for various 

 purposes, especially for melting the various mounting media, such 

 as gelatin, agar-agar, &c., and also, as we shall shortly see, for the 

 preparation of imbedding masses>for section cutting and a variety 

 of other purposes. One of the many pieces of apparatus which 

 have been devised to combine as large a number of the requirements 

 of the mounter in one construction as can be conveniently clone was 

 devised by Dr. P. Mayer and his colleagues. It is illustrated in 

 fig. 382. * 



W is the bath ; Z the tube by which it is filled with water; 1, 

 2, 3, 4 are glass tubes ; a is a pot for melting and clarifying the 

 paraffin, and this may be replaced by others for other needful 

 purposes ; b and c are half-cylinders with handles for imbedding ; t 

 is a thermometer bent at a right angle ; the horizontal leg ends in the 

 air-bath, and can be closed with a glass plate, which is of service for 

 biological as well as mounting purposes. The temperature in the 

 air-bath will be always about 10 less than that in the water-bath. It 

 serves w r ell for evaporating chloroform, etc. ; ^ is the thermometer for 

 the water-bath ; K, is a Reichert's thermo-regulator. The variation 

 in temperature is less than 1 C. ; r is the tube in w T hich the gas 

 and air mix, and f a mica chimney. There is a small independent 

 and removable water-bath, r, filled with water by means of rubber 

 tubes attached to lateral openings. It is supplied with a thermo- 

 meter, 2 , is warmed on the platform, F, and is intended chiefly for 

 fixing objects which are small in the right position in the imbedding 

 mass, usually known as ' orienting' objects, under a simple lens or 

 dissecting microscope. 



Slide-forceps, Spring-clip, and Spring-press. For holding 

 slides to which heat is being applied, especially while cementing 

 objects to be ground down into thin sections, the wooden slide- 

 forceps, seen in fig. 383, will be found extremely convenient. This, 

 by its elasticity, affords a secure grasp to a slide of any ordinary 

 thickness, the wooden blades being separated by pressure upon the 

 1 >i-ass studs ; while the lower stud, with the bent piece of brass at 

 the junction of the blades, affords a level support to the forceps, 

 which thus, while resting upon the table, keeps the heated glass from 

 contact with its surface. For holding down cover-glasses whilst 

 the balsam or other medium is cooling, if the elasticity of the object 

 should tend to make them spring up, the wire spring-clip (fig. 384), 

 sold at a cheap rate by dealers in microscopic apparatus, will be 

 found extremely convenient. Or if a stronger pressure be required, 

 recourse may be had to a simple spring-press made by a slight 



