WATER-BATHSPRING-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 3 x 1 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, will be required for various 

 purposes, especially for melting the various mounting media, such 

 as gelatin, agar-agar, Arc., 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 done was 

 de-vised 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; 6 and c are half-cylinders with handles for imbedding; ( 

 is a thermometer bent at a right angle ; the hori/.ontal legends 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 well for evaporating chloroform, Arc. ; ^ is the thermometer for 

 the water-bath; R is a Reiehert's thermo-regulator. The variation 

 in temperature is less than 1 C. ; r is the tube in which 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, t., 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 

 i 1 i ssecting 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, a fiords a secure grasp to a slide of any ordinary 

 thickness, the wooden blades being separated by pressure upon the 

 brass studs : while the lower stud, with the bent piece of brass at 

 the junction of the blades, a fiords 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), 

 si ild 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 



