116 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[August 6, 1870. 
Take two round-bottomed glass flasks, tbe one having 
a capacity four to eight times greater than the other. 
Adjust the smaller upon a water-bath, the larger at 10 
to 15 inches distance from the other, over a sink or 
large basin, and connect the two with glass tubing and 
perforated caoutchouc stoppers, so that the connecting- 
tube shall incline slightly downward from its bend close 
to the stopper of the small flask. The stopper of the 
small flask is also to have a second perforation, in w r hich 
is fitted a straight glass tube, 2 or 3 inches long, its 
lower end placed even with the lower end of the stopper. 
The upper end of this tube is very slightly drawn out for 
a quarter of an inch, and snugly fitted with 1 i inch of 
firm rubber tubing, the upper half inch of which is closed 
with a piece of glass rod of same diameter as the body of 
the tube. 
Now put an ounce or two of water in the large flask, 
and the material to be evaporated in the small flask ; 
close the stoppers perfectly by turning the flasks under 
them, and leave open the straight tube. Apply, by the 
water-bath, the limited degree of heat until it is imparted 
to the contents of the small flask; then move a lamp 
under the large flask until the water in it has boiled 
briskly, and the steam therefrom has escaped con¬ 
tinuously from the straight tube for some minutes. Now 
close the straight tube with its caoutchouc cap, at the 
same time removing the lamp from the large flask. 
When the latter has cooled somewhat, wrap it smoothly 
with linen netting or gauze, and lead upon it a minute 
stream of cold water, controlling the same as required. 
The liquid in the small flask boils briskly(if aqueous, boil¬ 
ing at 120° or 150° F.), and the refrigeration is governed to 
prevent too violent ebullition, lest liquid be thrown into 
the connecting-tube; the degree of applied heat is go¬ 
verned to the same end. 
An ordinary glass retort may be substituted for the 
small flask as an evaporating vessel, and its tubule may 
be fitted with a perforated stopper, admitting a thermo¬ 
meter. If there is not room in the stopper (of retort or 
flask) for both the thermometer and the steam-escape 
tube, the latter may be dispensed with by adjusting the 
stopper loose for escape of steam, and pressing it tight 
when the air is expelled. Flat-bottomed flasks favour 
equable boiling, but they are liable to collapse. 
As a condenser , I have used, instead of the large flask, 
a copper vessel, for more ready application of heat with- 
out danger of breaking, and for more efficient refrigera¬ 
tion. This copper receiver is made of conical shape, 
with rounded bottom, a vertical diameter twice its hori¬ 
zontal diameter, and a neck bent to the angle of about 
50° with the vertical axis of the vessel. The diameter of 
the neck is three-quarters of an inch, to receive a retort 
beak, the joint being covered with a section of caout¬ 
chouc tubing. Or it may be fitted with a perforated 
stopper, to receive the connecting-tube of the flask when 
evaporation is conducted in the latter. 
With linen netting to spread the water over the free 
surface of the condensers, the evaporation therefrom re¬ 
frigerates with a comparatively small supply of wnter. 
Using a copper condenser of the above-described shape, 
a vertical diameter of 12 inches, and capacity of 6 pints, 
attached to an 8-ounce glass retort containing distilla¬ 
tion promoters, I have vaporized 4 fluid ounces of water 
in sixteen minutes at the constant temperature of 128° F. 
By ordinary care in the expulsion of air and closure of 
the apparatus, exhaustion can be invariably secured, 
fixing the water-boiling point at below 130° F.; that 
is, atmospheric pressure equal to at least 25 inches of 
mercury may be removed and sustained by availing 
ourselves of the displacing effect of steam, and the 
contraction of condensing vapour, in very simple appa¬ 
ratus. 
Notwithstanding the illustrations of vacuum by con¬ 
densation, which abound upon the physical lecture-table, 
I do not know whether the devices suggested in this 
note have been tried or proposed for small chemical 
operations by any one else.* I have recommended them 
to students, and we have found them satisfactory for 
various analytical, experimental, and pharmaceutical 
operations. We have employed them chiefly in such 
evaporations as are performed for the residue only, or, at 
least, not for the quantitative recovery of the distillate, 
in various evaporations of quantitative analysis, in thn 
elimination of non-volatile alkaloids, in determining the 
organic matter in water, and in preparing fluid extracts. 
To evaporate at ordinary temperatures by hand-pump 
exhaustion is especially irksome in those cases when ap¬ 
plication of 125° to 150° F. is objectionable. And to 
connect a vessel under which heat may be applied with 
the air-pump involves quite as much labour as the ar¬ 
rangement of apparatus for exhaustion by condensation. 
American Journal of Pharmacy , from American Supplement 
to Chem. News, Jan. 1870. 
QUALITY AND ANALYSIS OF MILK. 
Dr. C. F. Chandler has published a report of the re¬ 
sults obtained in an extended examination of the milk 
supplied in New York, where it appears that the Metro¬ 
politan Board of Health takes cognizance of this among 
questions affecting the public. 
The following is an account of the method of analy¬ 
sis:— 
1. The water is determined by evaporating a weighed 
quantity of milk, either alone or soaked up in a known 
weight of pure, fine quartz sand. The residue is care¬ 
fully dried at 212° F., and weighed. The loss in weight 
represents the water, while the residue includes all the 
solid constituents. 
2. The salts are determined by carefully burning off 
the combustible portion of the solid residue obtained by 
evaporation, and weighing the incombustible ash. 
3. The butter and casein are determined by coagu¬ 
lating the milk with a few drops of acetic acid, boiling, 
washing the precipitate with water, and finally separat¬ 
ing the butter with ether, leaving the casein pure. On 
evaporating the ether, the butter is left behind, or the 
butter may be extracted by ether from the residue ob¬ 
tained by the evaporation of a quantity of milk, soaked 
up in sand. 
4. The sugar is generally determined by deducting 
the sum of the other constituents from 100. It may be 
directly determined by the polariscope, after the removal 
of the casein and butter, or it may be determined by an 
alkaline solution of copper. 
The Adulteration of Milk.— Numerous substances 
are mentioned as having been used, or as supposed to 
be used, for adulterating milk. Prominent among these 
are,— 
1. Water .—Adulteration with this substance is gene¬ 
rally detected by the specific gravity of the milk. Pure 
milk varies in specific gravity from P023 to P034, 
water being represented by l - 00 3. Milk is heavier than 
water, on account of the casein, sugar, and salts, which 
it holds in solution. Butter, on the other hand, is 
lighter than water, therefore the specific gravity of milk 
increases with the percentage of casein, sugar, and salts, 
while it diminishes with the percentages of water or 
butter. It is found that good milk generally has a spe¬ 
cific gravity of from 1 029 to P032. In testing milk the 
lower number is selected as a fair gravity for pure milk ; 
and whenever the gravity falls below this number the 
milk may be considered as containing an excess of 
water, and consequently poor in quality or adulterated. 
An instrument, called a galactometer, has been devised 
by Dinocourt, for the purpose of testing the quality of 
milk. It is simply an areometer, so graduated that 103 
* This method of producing a partial vacuum was employed 
by Barry (see U.S. Dispensatory, “ Evaporation of Extracts”) 
more than forty years ago in making extracts and volatile 
oils.— Ed. Ame'r. Journ. Pharm. 
