278 Progress in Science. [April, 



tube, which is closed by the pinch-cock. The requisite quantity of fluid is then 

 poured into the bottle, and the cork firmly inserted. Pressure is now made 

 on the india-rubber ball, taking care to close the hole with the finger. By 

 this means air is forced down the tube through the valve into the bottle. On 

 removing the pressure from the ball, the valve closes and the ball is re-filled 

 through the hole in its side, and the compression can be increased to the 

 necessary extent. The pinch-cock is now cautiously opened, and the fluid 

 rushes up the tube completely filling it and the nozzle ; the cock is then 

 closed, preventing further exit, and the instrument isready for use. The nozzle 

 is introduced and tied into an artery in the same way as with the ordinary 

 syringe. The inventor prefers glas« nozzles to those of metal, as they are 

 lighter, can be made very easily, and drawn out to very fine points. The in- 

 strument has the advantage of being self-acting, and leaving the uperator the 

 free use of both his hands, besides being more regular in its action than the 

 usual syringe, saving in the nands of those well practised in its use. 

 A form of apparatus nearly similar is employed by Dr. Rutherford ; in this, 

 however, the pressure is obtained by means of a column of water. 



The subject of mounting objects in the dry way has received some attention 

 from Mr. W. Ackland, F.R.M'S. Where thin cells are required, he employs 

 a ring of the varnish already mentioned in this Journal (vol. ii., N.S., p. 271) ; 

 this is allowed to become throughly dry before being used, a number of cells 

 being made and kept in stock. Where thicker objects are to be mounted, metal 

 or glass cells are used, coated on their upper surface with the same varnish. 

 The cover is fixed by being clipped to the cell ; heat is then applied, and the 

 varnish softened. Upon cooling, the cover is securely fastened. Where from 

 the nature of the object the slide cannot be safely heated, a thick disc of brass 

 sufficiently heated is applied to the cover with the same result. For attaching 

 delicate objects to slides, the following preparations are used : — 

 No. 1. Quinine Solution — 



Sulphate quinine .. .. .. 5 grains. 



Acetic acid 5 drops. 



Water 1 ounce. 



No. 2. Gelatine Solution — 



Gelatine 20 grains. 



Glycerine 5 drops. 



Quinine solution as above . . 1 ounce. 

 No. 3. Gum Solution — 



Gum tragacanth 5 grains. 



Glycerine 3 drops. 



Quinine solution 1 ounce. 



A small portion of No. 2 or No. 3 solution is spread upon the glass before the 

 cell is made. When the objects are to be attached to the glass they are 

 placed on the prepared gum or gelatine surface, and the slide placed under a 

 bell glass containing a saucer of water ; this softens the coating, and attaches 

 the minute objects. They are then dried under another bell glass, the moisture 

 being absorbed by chloride of calcium. The covers are then fixed as before 

 mentioned. The quinine solution may be used to prevent mouldiness in paste 

 or gum, and is an advantageous substitute for the bichloride of mercury usually 

 employed for this purpose, as the mixture is not poisonous. 



Mr. F. H. Wenham has communicated to the Royal Society* the formulas 

 for the improved microscopic objectives recently constructed by him. His 

 paper contains an account of the successive improvements in the construction 

 of object-glasses. A little before the year 1829, the three superimposed 

 achromatic lenses appear to have been in use; but no knowledge of their 

 pjoperties had as yet been arrived at, and it was not until Mr. J. J. Lister 

 announced his discovery of the aplanatic foci to the Royal Society in the same 

 year that any marked improvement took place. In the year 183 1, the late 

 Andrew Ross successfully constructed an object-glass on this principle, and at 



* Proceedings Royal Society, October 31, 1872. 



