1060 SUMMARY OF CURRENT RESEARCHES RELATING TO 



vessel, as well as its tubes as far as P, is filled with water, while 

 abovo it is a layer wo of etlier for temperatures about 40° C, or of 

 petroleum-ether for temperatures of 56°. P E is another glass vessel, 

 with an ascending limb, which contains mercury, and is connected by 

 means of a rubber tube with the cylinder Z S. Herein is a float T, 

 from which proceeds the wooden rod V U, terminated by the needle W. 

 The rod passes through a tube X Y inserted in a cork which closes 

 the end of the cylinder at Z. The tube X Y in addition to acting 

 as a guide-bearing for tho rod V U, has also the further object of 

 preventing, in case the pressure of tho ether should rise too high, tho 

 overflow of the mercury or tho bursting of the vessel. The upper 

 end of the float T U is so shaped that if it is pressed against the tube 

 X Y, the latter does not close but permits the mercury to ascend the 

 tube, after flowing over tho float. If the tube is only a few centimetres 

 high an overflow of the mercury is hardly conceivable, for such an 

 ascent w r ould correspond to a temperature difference of some degrees 

 Celsius in the incubator, and this, in consequence of the regulator, 

 never happens. The two glass tubes P It and S Z are clipped to an 

 iron burette-holder (fig. 231). 



The action of the apparatus is sufficiently simple. As the water 

 in the iron vessel gets hot, the ether expands and drives the water 

 in the glass bulb from M to C onwards, so that the mercury rises up 

 the tube E S and so presses on the float T, which in its turn raises 

 the needle W. The needle, as already mentioned, presses against 

 the lever, which if in the position W before, now rises to G, and by 

 this means moves the valve H J from F to J, thereby cutting off the 

 ascent of the hot air, all of which now passes out through K. As 

 the temperature falls, so do tho needle and the lever, the valves 

 consequently returning towards F. 



The temperature depends partly on the boiling point of the 

 fluid n o, and partly on the difference between the levels of and T. 

 The higher P E is placed the sooner the mercury reaches the float, 

 and the sooner therefore the heating process is interrupted. A bulbed 

 pipette is described which is used for filling M, N. 



Tursini's Photomicrographic Apparatus.* — In place of the small 

 dark chamber of the ordinary apparatus for photomicrography, Signor 

 Tursini proposes a camera obscura which is large enough to receive 

 the operator as well as the necessary instruments and reagents. The 

 Microscope and the preparation to be photographed are outside the 

 chamber, the image is projected into the interior. Near the Micro- 

 scope is an oblique aperture through which the operator, without 

 leaving the chamber, can regulate the position of the mirror, the 

 preparation, the fine-adjustment, &c. In this way the operations are 

 better watched, and therefore the results are better. 



Phototypic Process applicable to the Reproduction of Photomicro- 

 graphs.! — This method, which is the invention of M. A. Denaeyer, 

 depends on the insolubility of bichromate-gelatin produced by the 



* II Morgagni. 1886, p. 90. 



t Bull. Soc. Beige Mier., xii. (1886) pp. 92-6. 



