218 The Microscope. 



at 3, and consists of a conical tube, as before, but provided with a 

 perforated stopper, the side opening in which communicates with a 

 side tube. The perforation in the stopper, which is easily made by 

 a glass-blower, thus allows the overflow, when the stopper is in- 

 serted into the full tube, to pass into the side tube. The stopper 

 is then turned so as to cut off the urine in the latter from that 

 in the large tube, and the latter is thus made tight. After allowing- 

 it to remain at rest long enough to permit subsidence of all that 

 will settle, the stopper is gently turned and a drop taken ofP the 

 lower end upon a slide, to be examined at leisure with the micro- 

 scope. The cap, ground and fitted upon the lower end, is put 

 there as a precautionary measiu'e, as will be seen farther on. 



The tube shown at 4 is, we think, an improvement upon all of 

 the foregoing, for upon it there is no side tube to break off, and 

 everything is comprised in a small space. As will be seen by refer- 

 ring to the figure, there is a slight enlargement in the ground por- 

 tion of the stopper -end of the tube, this protuberance coming down 

 about one-half the length of the stopper, which is solid, and ground 

 to fit perfectly. The lower half, however, is provided with a small, 

 longitudinal slit or groove, the lower end of which communicates 

 with the interior of the tube, whilst the upper end just reaches the 

 enlargement in the side of the latter. Thus, in one position of the 

 stopper, there is a commiTuication between the tube and the outer 

 air, Avhilst in all the other positions the tube is quite shut. In all 

 these tubes care must be taken to fill them completely with the 

 urine, and to allow no bubl^les of air to remain therein. 



The first of these settling tubes was made without the ground 

 cap on the lower end, the latter being inserted into a small test- 

 tube for safety. At the suggestion of Mr. J. L. Smith, the test- 

 tube was made a part of the apparatus by fitting it (by grinding) 

 upon the conical end, and in its present form it serves to protect 

 the latter from dust and to prevent evaporation of the urine (or 

 other liquid) and consequent deposition of salts, if, for any reason, 

 the user should allow the tube to remain suspended for several 

 days. 



These tubes will be found very useful for collecting and con- 

 centrating into a small bulk the sediment contained in any liquid, 

 whether it be composed of urinary deposits, diatoms in process of 

 being cleaned, or anything of like nature ; and as the parts are all 

 of glass, the strongest acids may be used, excepting, of course,, 

 hydro-fliioric acid, without hai-m to the tubes. 



