and Laboratory Methods. 1893 



cables. From the other end of the fuse-block two similar cables connect with 

 the binding-posts of the knife-switch. When the electricity is turned into the 

 lamp by closing the switch, it passes to each carbon through the cables connected 

 with the right hand binding-posts of the switch. The arc is formed between the 

 proximate ends of the carbons which are shown as used on an alternating current 

 of 110 volts, and in about the proper adjustment to develop the maximum power 

 of the lamp. The carbons are fed together or singly by turning both feed-wheels 

 at the end of the horizontal shaft below the horizontal carbon at the same time, 

 or either one alone, as needed. The entire lamp may be elevated or lowered and 

 rotated to the right or left, and moved along the base-rods and clamped in any 

 position. The available light is derived from the end of the horizontal carbon 

 and falls directly into condenser number one, then passes through condenser 

 number two, both of which are in the condenser cell attached to the front of the 

 plate. The light next passes through the water-tank, then through condenser 

 number three, which is attached to the tank, then passes to the sub-stage con- 

 denser, if high power objectives are being used, next through the object mounted 

 on the stage of the microscope, then through the objective and, lastly, through 

 the amplifier and falls upon the screen. Th& sub-stage condenser is not used 

 with low power objectives, as it produces a cone of rays having too wide an 

 angle. The amplifier is a single plano-concave lens of five or six inches focal 

 length and may be used with any objective to increase the magnification of the 

 image on the screen. It is preferable to a regular microscopic ocular, as it 

 intercepts less light. A. H. Cole. 



University of Chicago. 



ELEMENTARY MEDICAL MICRO-TECHNIQUE. 



For Physicians and Others Interested in the Microscope. 



Copyrighted. 



VII— ABNORMAL CONSTITUENTS OF THE URINE. 



Albumin in the urine in any quantity should excite the attention of the physi- 

 cian, and frequent tests should be made to determine its cause. The nitric acid 

 test for the presence of albumin is very sensitive. Pour into a clean test tube 

 ^-inch of pure colorless nitric acid. Incline the tube and with a pipette allow 

 to run down the side of the tube, very slowly, an equal or greater quantity of 

 urine which will float upon the acid. This must be done carefully to prevent 

 the least mixing. If albumin is present a white ring of coagulated albumin will 

 appear at the point of contact. Colored rings are due to blood or bile pigments. 

 A cloudiness higher up is not albumin, but is due to precipitation of urates. 



It is much moregdesirable to test for quantity of albumin and quite as satis- 

 factory and rapid. 



Fill a graduated centrifuge tube with urine to the 10 c. c. mark, add 3 c. c. 

 of potassium ferrocyanide solution (potassium ferrocyanide 10 grams, distilled 

 water 100 c. c.) shake slightly and add 2 c. c. of acetic acid. Thoroughly mix 



