December 24, 1870.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
507 
Tent diffusion. On keeping the spirit for some hours at 
52°, effervescence continued, and there was little or no 
loss of spirit; at the end of the operation the neck of the 
flask had become only thinly encrusted with the pro¬ 
ducts of the effervescence, and the carbonate had only 
partly dissolved. The lumps on removal appeared ex¬ 
ternally to he hut little altered in structure. Internally, 
too, they were unchanged; for fragments yielded on 
.analysis oUol per cent, of carbonic anhydride, and 32'22 
per cent, of ammonia. The spirit proved to he a little 
weaker than before, dry pearl-ash separating a little 
water. It contained a little ammonium carbamate, still 
less ammonium carbonate, and a marked though small 
■quantity of ammonia. Left at a temperature of about 
0 ° for two days, it did not crystallize. 
Behaviour ivith Ammonia. —Concentrated ammonia- 
water in the cold dissolves out carbamate, and converts 
the acid carbonate into normal carbonate, either by re¬ 
moving half its carbonic anhydride, or by combining 
with it an atom of water. The commercial carbonate 
digested at 20°-2 5° in a closed vessel with a saturated 
solution of ammonia, as already described in the case of 
the normal and acid carbonates, slowly dissolves in ap¬ 
parently unlimited quantity, and the solution deposits 
on cooling crystals of ammonium carbamate, and a very 
little normal carbonate. The reaction may be thus re¬ 
presented :— 
(C 0 2 ) 2 0 H 2 (N H 3 ) 3 + NH 3 =2 C 0 2 (N H 3 ) 2 + 0 H, 
Behaviour when Heated ivith Anhydrous Potassium Car¬ 
bonate. —As already described, the gases evolved condense 
to carbamate, ammonia escaping, according to this equa¬ 
tion :— 
(C 0 2 ) 2 0 H 2 (N H 3 ) 3 + C0 3 lv 2 
Forming carbamate. 
= 2C0 3 KH + C0 2 + 2 NII 3 + HN 3 . 
The contents of the retort have been found, in accordance 
with this equation, to be more or less completely acid 
potassium carbonate.* For a short time after the mix¬ 
ture is made, ammonia is evolved in very small quantity 
at ordinary temperatures, and escapes in bubbles through 
the mercury into which the beak of the retort is made 
to dip, but this is probably due to the presence of a little 
moisture. It is only at from 50°-60° that a material re¬ 
action is set up ; and here a phenomenon presents itself 
which is of considerable interest. Nothing but ammonia 
is given off, and by maintaining the heat at 60°, this 
evolution of ammonia can be nearly or quite terminated 
before any carbamate-forming gases come off. It is not 
until the temperature is carried to 65° that the formation 
•of carbamate begins, and not until it is carried on to¬ 
wards and up to 80° that the whole of the carbamate is 
obtained. Hence the reaction occurs distinctly in two 
stages, according to the following equations:— 
1st stage : (C0 2 ) 2 0H 2 (NHA, + C0 3 K 2 
= NH 3 + CG 2 (NH 3 ) 2 , 2C0 3 KH. 
or = NH 3 + C0 2 (NH 3 ) 2 , CO 3 KH + CO 3 KH. 
2nd stage: CO n (NH 3 ) 2 , C0 3 KH 
= CO; + 2NH 3 + C0 3 KH. 
s__ __- 
To form carbamate. 
Further proof of a union of the acid potassium car¬ 
bonate with ammonium carbamate is afforded by the 
facts that on distilling the commercial carbonate with 
•calcium chloride, the components of the carbamate are 
•driven off at a temperature of 52°-65°, and that on heat¬ 
ing carbamate alone, it is converted into vapour at 59° 
or 60°; whereas in the present case the carbamate is not 
formed until the temperature reaches 65°, and passes on 
to 80°. The special interest of this point is its bearing 
* The commercial carbonate of ammonia and sodium car¬ 
bonate heated together have been used as a source of ammonia 
and bicarbonate of sodium. 
on the difficult question as to whether the commercial 
“ carbonate of ammonia ” is a double salt or only a mix¬ 
ture of salts. 
Behaviour when heated with Anhydrous Calcium Chloride. 
—At a temperature of o0°-o2°, the mixture evolves gases, 
a part of which condenses as carbamate, that escaping 
being carbonic anhydride; from this temperature up to 
60° or so, the reaction goes on steadily, but the escape of 
carbonic anhydride greatly diminishes ; how far the rate 
of formation of carbamate also slackens I have had no 
means of determining. The residue in the retort consists 
of unchanged anhydrous calcium chloride, of calcium 
carbonate and ammonium chloride. 
When solid calcium chloride, with about two atoms 
of water, is mixed in coarse powder with the commercial 
carbonate, the smell of ammonia entirely disappears; 
and soon after the mixture has been made it gets warm, 
swells up considerably, and evolves quantities of carbonic 
anhydride. When the action is over, on heating the 
mass to 50° or above, more carbonic anhydride is evolved. 
I happened in one case to be so fortunate as to mix the 
two in equivalent proportions. The consequence was 
that nothing was given off but carbonic anhydride and 
water. The residue was a porous mass of ammonium 
chloride and calcium carbonate. Treated with water, a 
solution was obtained which gave a faint precipitate with 
solution of ammonium carbonate and ammonia, and on 
the other hand a faint opalescence with calcium chloride. 
The insoluble matter was calcium carbonate. 
{To he continued.) 
MALT EXTRACT. 
BY ALBERT E. EBERT. 
The present time in the history of pharmacy may 
rightly be styled the era of “ scientific specialties.” The 
latest efforts in this direction are malt extracts. Two 
classes of preparations, under this title, are met with in 
the market, having widely different properties; one va¬ 
riety may be classed among alcoholic beverages; the 
other is purely saccharine in nature. To the first belong 
the preparations of Hoff and of Koch, the latter beai’ing 
the name of Liebig. Hoff’s extract has obtained a ready 
sale by aid of extensive advertising, a fact which is 
surprising, after the exposures made by Hager and Witt- 
stein. These chemists determined it to be simply a good 
article of brewer s beer , having an alcoholic strength of 
about 3 per cent., with an addition of marshmallow 
root, coriander, star-anise and grains of paradise, sweet¬ 
ened with glycerine or sugar, flavoured with the oils of 
lemon and orange, and coloured with burnt sugar. 
Koch’s preparation purports to be similar to Hoff’s, with 
the prominent advantage, well set forth in the words of 
the proprietor as follows :—“ Owing to the facilities we 
have in manufacturing in this country, we are enabled to 
sell Koch’s extract at the astonishingly low rate of $3.00 
per dozen, or 30 cents for a single bottle.” He magna¬ 
nimously offers to suffering humanity lager beer at only 
six times its retail value, while Hoff charges about 50 por 
cent, more for the same article! How thankful we should 
be for his fortunate “ advantage,” and we must also feel 
deeply grateful after perusing the circular which accom¬ 
panies this great medicine:—‘ ‘ The most eminent medi¬ 
cal authorities in Europe, as well as in this country, 
agreo that this new tonic is the best dietetic and healing 
remedy known to modern science, combining both the 
merits of a nutritious and palatable beverage, and the 
virtues of an unfailing medicine for general diseases of 
the lungs, the chest and the throat, while to those, in 
good health it serves as a pleasant table drink, promoting 
their digestion and restoring and invigorating their ap¬ 
petite—(for what?). This malt extract offers the most 
beneficial relief to the sick all in cases where the stomach, 
the lungs or the throat are affected.” 
The reader will say, “ But medical men do not recom¬ 
mend such nostrums.” In reply, we will state that we 
