244 
DR. ROBERT THOMSON ON MALT. 
The citric acid is often printed before as 
well as after the application of the mordant. 
In the latter case it is generally assisted by 
hisulphate of potash, or even sulphuric acid, 
by which the more expensive acid is econo- 
mized. 
14. MADDER AND LOGWOOD,— 
The cloth is impregnated with the aluminous 
mordant which is discharged on the white 
portions by the method just described. It is 
then dyed with madder in the usual way^ 
only a quantity of logwood is mixed with the 
madder. I'his logwood changes the madder- 
red to brown. 
15. COCHINEAL PINK. --The cloth in 
this case also is impregnated with the same 
aluminous mordant, and the white portions 
are discharged by means of citric acid, in the 
way described in a former paragraph. It is 
then dyed in cochineal, which communicates 
a very beautiful pink. 
For this beautiful dye we are indebted to 
America. Cochineal is the name given to a 
small insect which inhabits the cactus coccini- 
lifera, and three or four other species of 
cactus, on which it remains immoveable, de- 
riving its nourishment from the juices of the 
plant. It is a native of Mexico, and had 
been employed by the natives as a red dye. 
When the Spaniards entered the country in 
I5l8, it drew their attention, and in 1523 
Cortes received orders from the Court of 
Spain to procure as great a quantity of it as 
possible. The earlier Spanish writers des- 
cribe cochineal as an insect ; but it came af- 
terwards to be considered as the seed of a 
plant ; and this erroneous notion was not 
fully cleared away till about the middle of 
the eighteenth century. 
ON MALT. 
By Robert D. Thomson, M. D. 
( Continued from page 144 . ) 
1. The first step of the process consists in 
placing the malt in the steep, a square cham- 
ber, which is lined with stone and lime, and 
is usually sunk below the level of the barn 
floor, having been previously filled to the pro- 
per height with water.* The malt is allowed 
to remain here for not less than 40 hours, by 
legal regulations. The light seeds which 
swim on the surface are skimmed off, and the 
mass of grain is levelled, for the purpose of 
being gauged. The time during which the malt 
is allowed to remain in the steep varies, accor- 
ding to the wheel of the maltster. But the usual 
test of its fitness for being removed is thecapabi- 
lity of its extremities being squeezed together 
* Professor Lavini finds the composition of 
wheat as follows: 1. Ripe corn coiiiains 75 per 
cent, of starch ; uripe corn only 60 per cent. 2. 
Unripe corn contains | of its weight of mucous 
extractive matter. 3. In nnripe corn there is about 
iOth of gluten; in ripe corn 25 per cent. 4. The 
albumen is the same in both, 5. In unripe corn 
there is a gieeu resin, amounting to about ^Oih, 
which is probably converted into gluten and gum 
as vegetation advances. 6. Both contain oxides of 
copper, iron and manganese. —Mmoric della 
Reale Accadem dele Sciendi. Torino, xxxvii. 
between the fingers. New barley requires a 
longer period before it acquires this property 
than old does ; and ftigg- attains this consis- - 
tence in a shorter period than barley. By 
this preliminary step the grain undergoes a , 
partial germination. It absorbs water and 
swells ; English barley increasing ^ in bulk, 
Scotch barley and bigg 
In less than 24 hours after the grain has 
been introduced into the steep, the water . 
begins to acquire a brown colour, and a pe- 
culiar odour. If this water is evaporated to 
dryness a blackish-brown residue possessing a 
disagreeable taste remains, which consists of 
extractive and nitrate of soda, amounting in 
weight, tog^jorj^of that of the grain 
employed. About gggth of its weight of 
carbonic acid is likewise emitted, which re- 
mains dissolved in the water, and continues to 
be disengaged after the grain has been taken 
out of the steep. And hence it is, that in ten 
days the grain not only loses all its addition- 
al weight, but gradually becomes lighter than 
at first. Thus, loo grains of barley become, 
by steeping, 135. Exposed to the air for ten 
days they become 93‘8. After a month they 
weigh 96 4, and after two months 100* *8. 
Edwards, Colin, and Becquerel, have found 
that by causing grain to vegetate in water, 
acetic acid, sugar, and fermenting matter were 
secreted. The circumstance of the forms of | 
carbonic acid, in this first stage, shews us that , 
evolution is the preliminary step to germina- 
tion. 
The grain, after remaining in the steep, as 
has been said, for a period of not less than 40 
hours, is drained. It is then cast, or remov- 
ed, from the steep to the floor, where it is 
spread out in a rectangular form, to the depth 
of 16 inches, for the purpose of being gauged ; 
in this state it remains for 26 hours. The i 
barley in the couch always occupies a greater ' 
space than in the cistern, from the absence of 
the pressure of superincumbent grain. This 
increase, which is very great in small _ quanti- , 
ties, diminishes proportionally to the increase 
of the quantity of grain. Thus if 3 cubic inches 
of barley are placed in a cylindrical glass jar, 
graduated to tenths of an inch, and are cover- 
ed with water, in 96 hours the swell will be 
0*3 inch , or \gof the whole ; but, upon in- 
verting the vessel so as to shake the grain to 
the other end, it will occupy a bulk of 4*2 
inches, indicating a swell of more than 
On the other hand, when the quantity of 
grain is very considerable, it is found that 
sometimes its bulk in the steep exceeds that 
in the couch, but this may be, in some mea- 
sure, owing to errors in guaging. Consider- 
ing the bulk of grain in the steep to be expres- 
sed by loo, then the greatest bulk in the 
couch is 138, the least 110.6, the average 
121‘6. The officer of excise takes what is 
called the best guage, both in the couch and 
steep, or he takes the measurement of the 
grain when it has acquired its greatest bulk. 
One-fifth IS subtracted from the bulk thus 
obtained, and the number obtained is con- 
sidered as equal to the quantity of clean malt 
produced. The duty is charged accordingly^ 
whether correctly or not seems doubtful. 
