142 
DR. THOMSON ON MALT. 
the piece is passed through a strong caustic 
alkali, and then allowed to fall into a vessel 
containing chloride of lime. This converts 
the manganese into sesquioxide. wdiichhasa 
strong affinity for cotton. 
10. CHINA BLUE.— Indigo may be 
fixed upon cotton in a variety ofways. By 
having it with orpiment and caustic potash, 
it is deoxidized and dissolved. If gum-senegal 
or basted starcli be not dissolved in thesolution, 
it forms what is called pencil blue, which may 
be printed upon cloth by means of the cop- 
per roller, or by the block from a sieve of a 
peculiar kind. Applied in either of these 
ways, the indigo soon recovers its blue colour, 
and being no longer soluble, it remains upon 
the cloth, while water removes the substances 
with which it was mixed. 
By another process, indigo in the blue state 
is mixed with orpiment in a solution of sul- 
phate of iron,anddeoxidized after being printed 
on the cloth, by alternate immersions in 
lime and copperas. It is known that indigo 
in the doxidized or white state, is soluble in 
alkalies, forming a yellow coloured solution. 
This solution deposits its deoxidized indigo on 
the cloth by mere contact. In this way the 
indigo which is at first loosely laid upon the 
fibres, and easily removeable by washing, is 
slowly combined with them, and thus becomes 
fixed on the cloth. A large quantity of iron 
is necessarily attached to the cloth during this 
process, and a continued action of sulphuric 
acid is necessary for its removal. 
A third process consists in dissolving pow- 
dered indigo in a hot solution of potash, and 
stannite of potash, or by boiling it in potash 
or soda, along with metallic tin. It is then 
precipitated in a white state by muriatic acid, 
and the precipitate being thickened and mixed 
with fresh chloride of tin, is printed on the 
cloth. When dry, the piece is immersed in 
a solution of carbonate of soda. The indigo 
becomes yellow by combining with the soda, 
and in this soluble condition, attaches itself 
permanently to the cloth. It soon afterwards 
becomes blue, by the absorption of oxygen 
from the atmosphere. 
U. CATECHU BROWN.-This impor- 
tant dy-stuff, formerly known by the name 
of terra japonica, is procured by boiling the 
brown heart wood of the acacia catechu, or 
khair-tree. It is obtained by simply boiling 
the chips in water, until the inspissated juice 
has acquired a proper consistency. The 
liquor is then strained, and soon coagulates 
into a mass. It comes to this country both from 
Bombay and Bengal, It consists chiefly of 
tannin, but contains also a little alumina, 
which may perhaps assist in fixing the colour 
on the cloth. 
The catechu is dissolved in acetic acid ; a 
solution of copper and sal ammoniac is added to 
it, and the whole printed on the cloth. It is 
allowed to stand a few days, during which the 
colourdeepens very much, and is then worked 
off. 
CHROME pRANGE.— The dichromate 
oflead is precipitated upon the surface of cot- 
ton cloth, by printing on it a solution oflead, 
and then immersing the cloth in a hot solution 
of a chromic salt of potash, or of lime, contain- 
ing a slight excess of base; or, it is some- 
times obtained from the yellow chromate of 
lead, produced from the bichromate of potash, 
by abstracting a portion of its acid in hot 
lime-water.. 
To be continued. 
ON MALT. 
By Rorbet D. Thomson, M, D. 
(Continued from pages 99.) 
Bigg and bear are susceptible of exposure 
to greater vicissitudes of climate than barley is. 
They require also less time to attain to 
maturity, 'fhus, the averagetimein which they 
usually remain in the ground is from ten to 
fourteen weeks; whilebarley liesfromfourteen 
to twenty weeks. An instance is recorded 
where the interval between seed time and 
harvest, in the cases of hear, was only nine 
weeks; and another, on the contrary, where 
barley was twenty-six weeks of ripening. Bear 
and bigg in common years are malted by the 
Highlanders, but in those seasons which are 
un propitious for the ripeni.ng of oats, they 
form the chief article of food. Hence, the 
legislature have been induced to charge a 
duty of 2s. 7d. per bushel on malted barley, 
and 23. only on malted bear and bigg. In 
1789 and 1799, which were late years, the 
whole of the barle'y sown in Aberdeenshire 
was destroyed, a circumstance which operated 
RO powerfully upon the farmers, that in 180-3, 
little, more than 100 quarters were raised, 
while from 35,000 to .50,000 quarters of bear 
and bigg were produced. 
Now, Aberdeenshire consists of 832,000 
English acres and possesses a mean tempera- 
ture of 4U. 14. 
Mr. Forbes Royle observed barley growing 
on the Himalah mountains, at an elevation of 
8000 feet, the mean temperature of the place 
being 55^ F. But some very important deduc- 
tions have been obtained by M. M. Edwards 
and Colin, ^ from their interesting experi- 
ments upon the germination of different kinds 
of grain. They exposed barley, wheat and 
rye to a cold equal to that at which mercury 
freezes or— 38'6‘> F. for 15 minutes, and found 
that their vegetative powers were not in the 
least deteriorated. They ascertained tliat if 
barley, wheat, French beans or linseed were 
immersed for a quarter of an hour in water at 
the temperatureof I54f, the powerof germina- 
tion was completely destroyed, and it was not 
till the heat of thewater was reduced to 122«, 
that these kinds of grain after being immersed 
in it would vegetate. Hence,. in water, 122o 
maybe considered the highest limit at which 
it is possible for barley to grow. But the 
temperature varies according to the media 
through which the heat is communicated. 
Thus these seeds if exposed to a temperature 
above 143g^ in vapour, or 167 in dry air, are 
deprived of their vegetating properties. While 
wheat, barley, oats and rye, when kept in hot 
sand possessing a heat of 113o, would not ger- 
Anii, de Scien. Nat. for May, 1836, 
