— 22 — 



2. A boiling flask, fig. 2, known to chemists as a 100 c.c. (cubic 

 centimeter) Erlenmeyer flask. 



3. Two small measuring tubes, one with a mark on its»side in- 

 dicating a volume up to that mark of 2% c.c, and the other with 

 a mark at 4 c.c. capacity. 



4. A pipette, of glass, consisting of a short, wide, glass tube 

 terminating in two long, narrower tubes, and with a mark on the 

 upper one of these narrow tubes indicating a capacity of 5 c.c. 

 Mr. Cochran, in his original paper, suggests the use, in place of 

 this, where rapid work is desired, of a little nickel dipper, holding 

 when full just 5 c.c; but the difficulty of emptying the milk from 

 this into the boiling flask without loss, and without getting any 

 of it on the neck of the flask where it would not be reached by the 

 chemicals with which it is to be treated, seems to me so great, 

 that till I shall have been able to try such a method of measuring, 

 and thus to learn how large an error is likely to be introduced, I 

 prefer to recommend the pipette. 



5. A copper boiling vessel or water bath. This may be circu- 

 lar or oblong, and of any size desired, and about four inches in 

 depth ; a false bottom perforated with a number of small holes is 

 soldered in, about two and a half inches from the bottom ; the 

 top, which is soldered on, has two and a quarter inch circular open- 

 ings, which may be about a quarter of an inch apart. If the dish 

 is circular, and nine inches in diameter, eight of these openings 

 can be put in, one of them being in the center. This boiling ves- 

 sel may be heated on an ordinary stove, or a small oil stove, in- 

 stead of the gas burner that would naturally be used in the 

 chemical laboratory. 



The chemicals required are : 



1. Commercial sulphuric acid, of good quality. Great care 

 must be taken not to get even a drop of it on the hands or clothing. 



2. Acetic acid, full strength. 



3. Ordinary washed ether. Great care should be taken not to 

 pour this from the can containing it while ?iear a flame of any 

 kind, and to keep the can always well stopped. 



A pound of each of these will suffice for about two hundred 

 analyses. 



A set of this apparatus, with this supply of chemicals, and in- 

 cluding six fat measures and six boiling flasks, will cost about 

 $7.00 : with half as many fat measures and boiling flasks, about 



