208 



NATURE 



\_yan. lo, 1878 



plaster of Paris against small splinters of wood by means 

 of a jet of steam. 



In the discussion which followed the reading of that 

 paper Dr. Crompton suggested the ether spray, such as is 



Feg. I, 



used in surgery, as a means of obtaining a frozen fog, 

 and Prof. Reynolds explains how after various attempts 

 he had succeeded in combining a spray of ether and 

 water so as to form artificial stones. He then proceeds 

 as follows :- - 



The apparatus is shown in Fig. r. It consists of a 

 brass tube half an inch in diameter, one end of which is 

 connected with bellows capable of maintaining a constant 

 pressure of about 18 inches of water, on the other end of 

 the tube is a cap over the end of which is a flat plate or 

 diaphragm having a central opening \ of an inch in 

 diameter which forms the aperture for the blast. Enter- 

 ing through the sides of the main brass tube are two 

 small brass tubes which reach to within \ an inch of the 

 plate and into the ends of which are sealed, fine glass 

 capillary tubes, the glass being very thin ; these protrude 

 just through the middle of the aperture, the one about , \ 

 of an inch and the other ^j. Through these tubes the 

 water and ether are separately introduced into the blast 

 to form the spray, and it is mainly on the adjustment of 

 these tubes that the efficiency of the apparatus depends. 

 It is essential that the ether tube should be slightly the 

 longest, otherwise the ends become stopped with ice, and 

 I find it better that the ether tube should be somewhat 

 larger than the water tube. The bore of the tubes must 

 be very small, but this is not sufficient, for unless the 



glass is very thin the spray will not be finely divided. 

 Both the ether and water are forced through the tubes 

 from bottles by connecting the interiors of these bottles 

 with the bellows, and the quantities of ether and water 

 are regulated either by raising and lower- 

 ing the bottles or by means of the cocks 

 in the pipes. 



The tube is fixed in an ordinary retort- 

 stand, so that the blast is vertical. If then 

 a small splinter of wood is held pointing 

 downwards into the spray, a lump of ice 

 forms on the end of the splinter, and this 

 Jump has all the appearance of the hail- 

 stones. It is quite white and opaque, it is 

 conical in form and has a rounded base and 

 striated surface. 



In this way I have formed stones from 

 half to three-quarters of an inch in dia- 

 meter. When, however, the stones are 

 growing large it is necessary to move this 

 splinter so as to expose in succession all 

 parts of the face of the stone to the more 

 direct action of the spray. 



When using this apparatus in a warm 

 room I have found it best to fix a pad of 

 blotting paper over the jet at a height of 

 10 or 12 inches. The surface of this pad 

 is cooled by the spray and prevents radia- 

 tion from the ceiling, which otherwise tends 

 to melt the top of the stone. For a similar 

 reason I have found it well to surround 

 the blast with a wide cylinder or inverted 

 cone of paper, which keeps off radiation 

 without interfering with the action of the 



By sticking several pieces of wood into 

 the pad, pointing downwards, a number of 

 stones may be made at once. 



In Fig. 2 a medium-sized stone as well 

 as one of the largest stones are shown at- 

 tached to the splinters of wood. The 

 surface of the cone, where continuous, is 

 truly conical, or rather pyramidal, but this 

 surface is broken, as it were by steps, and 

 a very marked fact is that all the continuous 

 surfaces have the same vertex, and hence 

 the different conical surfaces to which they 

 belong, have not the same vertical angle, 

 the surface being exactly such as would be acquired by 



Fig. 2. 



the fragments of a sphere so constituted that the fracture 

 tended to follow radial lines. 



