406
TV, NIEHLS.
% . SCALE
evaporation has lowered D, sufficiently more water will run into tlie bath to take the place of that evaporated. A small stream of water flows constantly out at C and into the sink, but it need be very sniall indeed. If the bulb E enters the bath through a place needed for evaporations, a sniall copper cylinder slightly larger than the opening and having a narrow strip cut out of it for D to move up and down i n , may be placed over it as in the cut. Of course, the float may be placed i n a side tube soldered to the bath with water-connection to it. If one cannot make it of glass it could easily be coiistructed of metal ti!* any tiiinian. I fiiid also that the same idea works adinirably for constant feeding of a small platinum dish in evaporating large quantities of ivater or other liquids for analysis of residues. I n such cases the tube I)’ is directly connected with a bottle holding several liters of water i n the iiianner illustrated i n the cut at the right. Ah’D’ falls through evaporation of the water in m , air enters through 1, and nxter drops out at ?z till D’ rises so that 71 is liiglier than the bottom of L when it stops, and thus the level in is constant. In this case the tube D’ is very sinall so that the bulb C a n be verj. sniall and still hold it up. In the one I use, the bulb is onl!. I .=j ~ 1 x 1 .i i i diameter and the tube )L so close to it that it can be used i n a crucible. It is very easy to clean the float from the slight residue clinging to it at the end. 1 use the satlie apparatus for washing precipitates with a large aniount of water, placing the bulb in tlie funnel on the surface of the wash-water. H O I V D O I S COLLR 5 1891
T
H E Koettstorfer figure of a fat or resin is the number of
milligrams of potassium hydroxide required to saponify one gram of the substance. It is determined by adding to a
