ALB 
chemists have agreed to denominate albu- 
men. The white of an egg, however, is not 
pure albumen. It contains, combined with 
it, some soda and some sulphur : but as albu- 
men is never found except combined with 
these bodies, and as no method is known of 
separating it without at the same time alter- 
ing the properties of the albumen, chemists 
are obliged to examine it while in combina- 
tion with these bodies. 
Albumen dissolves readily in water, and the 
solution has the property of giving a green 
colour to vegetable blues, in consequence of 
the soda which it contains, Wjien albumen 
is hea!,ed to the temperature of 165°, if coa- 
gulates into a white solid mass ; the consist- 
ency of which,, when other things are equal, 
depends, in some measure, on the time dur- 
ing which the heat was applied. The coagu- 
lated mass has precisely the same weight that it 
had while fluid. T his property of coagulat- 
ing when heated is characteristic of albumen, 
and distinguishes it from other bodies. 
The taste of coagulated albumen is. quite 
dift'erent from that of liquid albumen : its ap- 
pearance, too, and its properties, are entirely 
changed ; tor it is no longer soluble, as before, 
either in hot or in cold water. 
Tile coagulation of albumen takes place 
even though air is completely excluded; and 
even when air is present, there is no absorption 
of it, nor does albumen in coagulating change 
its volume. Acids have the property of coa- 
gulating albumen, as Scheele ascertained. Al- 
cohol also produces, in some measure, the 
same effect. Heat, then, acids and alcohol, 
are the agents which may be employed to 
coagulate albumen. 
Scheele and I'ourcroy have ascribed the 
coagulation of albumen to the addition of a 
new substance. According to Scheele, ca- 
loric is the substance which is added. Pom- 
eroy, on the contrary, affirms that it is oxy- 
gen- 
Albumen then is capable ot existing in two 
states ; the one before it lias been coagulated, 
and the other after it has undergone coagu- 
lation. Its properties are very different in 
each. It will be proper, therefore, to con- 
sider them separately. 
1. Albumen, in its natural state or uncoa- 
gulated, is a glary liquid, having little taste, 
and no smell. When dried spontaneously, 
or in a low heat, it becomes a brittle transpa- 
rent glassy-like substance, which, when spread 
thin upon plain surfaces, forms a varnish,. and 
is accordingly employed by bookbinders for 
that purpose. When thus dried, it has a con- 
siderable resemblance to gum arabic, to which 
also its taste is similar. The white of an egg 
loses about 4-5ths of its weight in drying. It 
is still soluble in water, and forms the same 
glary liquid as before. 
Uncoagulated albumen soon putrefies un- 
less it is dried ; in which state it does not un- 
dergo any change. 
2. When albumen is coagulated either by 
heat, alcohol, or acids, it is an opaque sub- 
stance of a pearl white colour, tough, and of 
a sweetish mucilaginous taste. It is no longer 
soluble in water, and is not nearly so suscep- 
tible of decomposition as uncoagulated albu- 
men, Mr, Hatchett kept it for a month 
under water, and yet it did not become pu- 
trid, It is to the experiments of this inge- 
nious chemist that we are indebted for almost 
every thing at present known relative to coa- 
ALB 
gu late cl albumen. By drying it in the tem- 
perature of 212°, he converted it into a brittle 
hard yellow substance, semitransparent like 
horn. r 
These properties indicate sufficiently that 
coagulated albumen is a very different sub- 
stance from uncoagulated albumen. During 
the coagulation its component parts must ar- 
range themselves differently. 
From the effects of nitric acid on albu- 
men and its products, when subjected to de- 
structive distillation, it lias been concluded 
that it consists of carbon, hydrogen, azote, 
and oxygen, in unknown proportions. As it 
yields more azotic gas to nitric acid, it has 
been considered as containing more of that 
principle than gelatine. It is obvious, how- 
ever, that it does not differ much from that 
body, as nitric acid spontaneously converts it 
into gelatine. Albumen forms the membra- 
nous parts of many shells, sponges, &c. It is,- 
in short, one of the most important and ge- 
neral animal substances. 
The property which albumen has of being 
coagulated by heat renders it a very useful 
substance for clarifying fluids. See Thomp- 
son’s Chemistry. 
Albumen, vegetable. This substance was 
discovered by I'ourcroy, who observed that 
the clarification of the expressed juices of an- 
tiscorbutic plants was effected by the sponta- 
neous coagulation of their colouring matter, 
at the temperature of boiling water, on which 
account he was led to examine whether this 
property did not depend on the presence of 
albumen. He obtained the juice of two 
pounds of young cresses, and filtered it while 
cold through blotting paper, and thus sepa- 
rated the grosser parts of the colouring fecula ; 
the liquor was still of a bright green, and upon 
being exposed in a broad shallow vessel to 
the air at the temperature of 80° Fahrenheit, 
in two hours it became turbid, and deposited 
green matter, becoming itself almost colourless; 
in this state it was exposed to the heat of boiling 
water, and in a fesv minutes there separated a 
quantity of whitish fiocculent matter. Ano- 
ther portion of the same liquor exposed to the 
air, deposited, at the end of two days, a simi- 
lar coagulum ; and the same effect was pro- 
duced on a third portion by the addition of 
sulphuric acid. T his substance exhibited all 
the properties of animal albumen. 
Albumen has since been found in the roots 
of various vegetables ; also in wheat, and the 
farinaceous seeds; and in general in all the 
green and succulent plants. The acid pulp 
of fruits are totally destitute of this substance, 
but they abound with jelly ; and it is sup- 
posed that, in all these cases, there is a con- 
version of albumen into jelly, by the gradual 
evolution of the acid, and fixation of oxygen. 
ALBURNUM, the soft white substance 
found in trees between the liber, or inner 
bark, and the true wood, and which, in pro- 
cess of time, is itself converted into that sub- 
stance. It is found in the largest quantities in 
trees which are vigorous. In an oak six inches 
in diameter this substance is nearly equal in 
bulk to the wood. In a trunk of one foot dia- 
meter, it is as one to three and a half ; of two 
and a half feet diameter, as one to four and a 
hafi, &c. but these proportions vary according 
to the health and constitution ot the trees. 
The alburnum is frequently gnawed in pieces 
by insects, which lodge in this substance, and 
are nourished from it. 
F 2 
A L C U 
ALCA, or Auk, in ornithology, a genus of 
the order of anseres, r i he beak ot this genus 
is without teeth, short, convex, compressed, 
and frequently furrowed transversely : the in- 
ferior mandible is gibbous near the base ; the 
feet have generally three toes. 1 here are 12 
species of the alca, of which the most remark- 
able are, 
1. Alca alle, the little auk, or black anil 
white diver, with a smooth conical bill, a white 
streak on the belly and wings, and black feet. 
The size of this species exceeds not that of a 
blackbird. It is not very common in Eng- 
land. It seems to be most plentiful towards 
the north, being met with in various parts as 
far as Spitzbergen. It is common in Green- 
land, in company with the black-billed spe- 
cies ; feeds on the same food ; and lays two 
blueish eggs, larger than those of a pigeon. 
It flies quick, and dives well ; and is always 
(lipping its bill into the water, while swimming 
or at rest on the water. It grows fat in the 
stormy season, from the waves bringing 
plenty of crabs and small fish within its reach ; 
but from its size it is less sought after than the 
others. In Greenland it is called the ice-bird, 
being the harbinger of ice. r Ihis species is, 
sometimes seen of a pure white. 
2. A. Arctica, known in England by the 
name of puffin. See Plate Nat. Hist, fig. 
8. These birds are found upon several of the 
rocky coasts in England, in Ireland, North 
Britain, Iceland, and Greenland. They fre- 
quent Carolina in America during winter, and 
have been met with in Sandwich-sound, where 
the natives ornament the fore, parts and collar 
of their seal-skin jacket with the beaks of 
them. On the coast of Kamtschatka, and the 
Kurile islands, the inhabitants wear the bills 
of the arctica about their necks, and their 
priests put them on with a proper ceremony, 
in order to procure good fortune. They ar- 
rive at their breeding places here about the 
first week in May, and endeavour to dislodge 
the rabbits to save, the trouble of making 
holes for themselves. The female lays but 
one egg, and the young are hatched in the 
beginning of July, and about the middle of 
August they take their flight. The young 
that are late hatched, become the prey of 
falcons, &c. Notwithstanding their neglect 
of the young at this time, on every other oc- 
casion they are very attentive to them. They 
will suffer themselves to betaken by the hand, 
and use every means of defence in their 
power to save them ; and if held by the wings, 
will tear their bodies, as if actuated by de- 
spair, and when released, instead of flying 
away, will hurry again into the burrow to 
their young. 
3. Alca Cirrhata, so called by Dr. 
Pallas, or tufted auk, is somewhat bigger than 
the common puffin, and the colours much the 
same : the bill is an inch and three quarters 
in length, the same in depth at the base, and 
crossed with three furrows; over each eye 
arises a tuft of feathers four inches in length, 
which falls elegantly on each side of the neck, 
reaching almost to the back; and white as 
far as they arc attached to the head, but 
afterwards of a fine buff yellow; the legs are 
of a bright red ; the claws black. The female 
is principally distinguished by having the bill 
crossed only with two furrows instead of three. 
This species inhabits the shores of Kamtschat- 
ka, the Kurile islands, and those intervening 
between Kamtschatka and America. In man- 
