September 23,1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
241 
DETERMINATION OF GLACIAL ACETIC 
ACID. 
BY FR. RUDORFF. 
The volumetric estimation of acetic acicl by means 
of a standard solution of caustic soda cannot claim 
very great accuracy, because the change in colour of 
litmus is not sufficiently marked. Mr. Riidorff has 
therefore proposed a new method, readily executed 
and very accurate, which consists in determining 
the solidifying-point of the acid. 
Commercial glacial acetic acid is never free from 
water, the solidifying-point of various samples rang¬ 
ing from 7° C. to + 14° C. In order to obtain some 
perfectly anhydrous, a quantity of the commercial 
acid was placed in a cold place, until about three- 
fourths of it had solidified; the liquid part was se¬ 
parated, and the solid portion was remelted, cooled 
and solidified. The liquid was again separated, and 
this operation repeated until at last a constant soli¬ 
difying-point was obtained ; this point gradually 
rose after each separation of liquid, as shown in the 
following observations, made with a sample of about 
two pounds:—12°'5, 15°T, 16°T, 16°-4, 16°-65, 16°-7, 
16°-7, 16 u -7 C. 
It is advisable to leave the liquid, in which some 
solid acid separated overnight, in a room the tempe¬ 
rature of which is a few degrees below the solidifying- 
point of the acid ; the last then separates in foliated 
masses, from which the liquid may easily be poured 
off; this liquid, of course, contains * more water 
than the remaining solid acid. 
The solidifying-point of this solid acid is 16°-7 C.; 
its boiling-point is 117 0, 8 C. With gradual cooling 
the temperature may be reduced to 10°, and even 
8°'5, and the acid may be shaken without solidifying; 
but a single grain of solid acid sets the whole mass 
at once, the temperature rising to 1G°‘7 C. When 
melted by placing the vessel in water of about 25° C., 
the thermometer placed inside the acid indicates 
1G°‘7 C. as long as a considerable quantity of solid 
substance remains,—proving that the melting and 
solidifying points are at the same temperature. 
100 parts by weight of anhydrous acid were mixed 
with a weighed quantity of water, and the solidify¬ 
ing-point of the mixture was determined. It must 
be remembered that a mixture of two liquids does 
not solidify as such, but only one of them, in this in¬ 
stance acetic acid; while the water remains fluid. 
Aqueous concentrated acetic acid acts similarly to 
saline solutions, of which the author has shown that, 
on freezing, the water alone solidifies. 
The proportion of acid and water would be altered 
if much acid solidified; it is therefore necessary to 
take care that only very little acid separates. This 
is effected by cooling the mixture to within one de¬ 
gree of the solidifying-point, approximately deter¬ 
mined ; after which a particle of solid acid is added, 
and the liquid well stirred with a delicate thermo¬ 
meter. Repeated experiments show a difference of 
not more than 0°T C. The following table contains 
the results of a series of observations, viz. :— 
ICO parts by weight of 100 parts of mixture Solidifying- 
acid mixed with water, containing water. point. 
Degrees. 
0 0 Water. 0‘0 Water -f- 1G’7 C. 
0-5 0-497 16-65 
1-0 0-990 14-80 
1-5 1-477 14-00 
Third Series, No. 65. 
100 parts by weight of 100 parts of mixture Solidifying, 
acid mixed with water. containing water. point. 
2"0 Water. 
T961 Water 
+ 13-25 
3-0 
2-912 
11-95 
4-0 
3-84G 
10-50 
5-0 
4-761 
9-40 
6-0 
5-660 
8-20 
7-0 
6-542 
7-10 
8-0 
7-407 
6'25 
9-0 
8-257 
5-30 
io-o 
9-090 
4-30 
11-0 
9-910 
3-60 
12-0 
10-774 
2-70 
15-0 
13-043 
— 0-20 
18-0 
15-324 
2-60, 
21-0 
17-355 
5" 10’ 
24-0 
19-354 
7-40- 
The table shows that especially in concentrated 
acid one-tentli of a percentage of water maybe accu¬ 
rately determined. 
Several other substances act like water in re¬ 
ducing the solidifying-point of acetic acid; for in¬ 
stance, sulphuric acid, alcohol and several salts, 
soluble in the acid. A mixture of 100 parts of 
acetic acid and 0"5 part of sulphuric acid solidifies 
at 16°-4 C.; 100 parts of acid and 1*8 parts of alcohol 
at 15°"25 C. The influence of water may be partly 
counteracted by sulphuric acid; thus, from a mix¬ 
ture of 100 parts of acid and 10 parts of water the 
acid separates at 4° - 3 C.; an addition of 2 parts of 
sulphuric acid raises the point to 5°"8 C., and 20 
parts of sulphuric acid added to the same mixture 
bring the point up to 10°"7 C. 
The solidification of acetic acid takes place even in 
summer with absolute accuracy. The acid is cooled 
to about 10° or 12° C., a particle of solid acid is 
added, and on shaking the bottle the acid solidifies 
forthwith. A small quantity of solid acid is easily 
obtained by placing a test tube containing a few 
drops of liquid acid in a mixture of chloride or nitrate 
of ammonium and cold water.— Wittsteiris Viertel - 
jahrsschrift fur prciJct. Pharm., 1871, p. 84. 
ERGOT OF RYE. 
BY DR. T. C. HERRMANN. 
Although ergot of rye has been repeatedly sub¬ 
jected to chemical analysis, there are several ques¬ 
tions touching its component parts which have not 
been fully explained, and for this reason Dr. Herr¬ 
mann has chosen the subject for his inaugural dis¬ 
sertation. 
One of the constituents of ergot which required 
further investigation is the fatty oil, which, though 
not differing from other oils in general characteristics, 
is peculiar so far, as according to Manassewitz, it 
readily saponifies with caustic soda, but not at all 
with caustic potash; this statement Dr. Herrmann 
was enabled by his investigation to distinctly con¬ 
tradict. 
20 ounces of powdered ergot were exhausted with 
ether, the last separated by distillation, and the oif. 
which amounted to 6 ounces, subjected to analysis. 
It was of a brownish-yellow colour, ot aromatic 
flavour and acrid taste, viscid, and its sp. gr. was 
-9249, it was not drying. 
It consisted chiefly of palmitic acid, oleic acicl 
