ALG A. 767 
necessary to employ the tenth part of what is necessary when 
isinglass is used. Jellies prepared from species of Gelidiwm, 
Laurencia, &c., are much employed for food in China, Japan, &e. 
The so-called Japanese isinglass consists of numerous Algze, but 
more especially of Gelidiwm cornewm, Gloiopeltis tenax, and 
Endocladia vernicata. The edible birds’ nests, so highly valued 
for food in China, owe their properties probably in part to 
certain species of Algze, but essentially to, the secretions of the 
swallows by which they are constructed. 
In medicine the above-mentioned nutritious Algze may be 
used for their emollient and demulcent properties. Several 
species of Algve, particularly Fucus vesiculosus, have been also 
employed as remedies in goitre and scrofulous diseases. They 
owe their beneficial effects in such cases, principally, to the 
presence of a small quantity of iodine. The ashes obtained by 
burning many species of Algze in the open air form the substance 
called kelp, which was formerly much used for the preparation 
_of carbonate of sodium, but this is now more cheaply obtained 
from sea-salt. Jodine is, however, still prepared from kelp.* 
Some Alge have been reputed to possess vermifugal properties ; 
noue are knuwn to be poisonous. 
Several Algze are remarkable for imparting colours to water, 
snow, &c. Thus, Protococcus atlanticus gives a red colour to 
certain parts of the Atlantic ; P. nivalis contributes to commu- 
nicate a red colour to snow ; and P. viridis, a green tint ; Doli- 
chospermum Thompson imparts a green colour to some Irish and 
Scotch lakes ; the red colour of the Red Sea is also in part 
attributed to the presence of Trichodesmium erythreum, &e. &e. 
Dr. Robert Brown has also shown that the discoloration of the 
Arctic Sea is due to Diatomez, but principally to Melosia 
arctica, and that these form the brown-staining matter of the 
‘rotten ice’ of northern navigators. 
Alaria esculenta, Bladderlocks, Hen-ware, or Honey-ware, contains man- 
nite. It is employed for food in Ireland, Scotland, Iceland, and other 
northern regions. Berkeley says that ‘it is the best of all the esculent Algz 
when eaten raw.’ : 
Chondrus (Sphzrococcus ).—C. crispus is the source of the so-called Carra- 
geen or Irish Moss. It possesses nutritive, emollient, and demulcent pro- 
perties, and may be employed in the form of a decoction or jelly, in 
pulmonary complaints and other affections. Bandoline or fixature, used for 
stiffening the hair, and other purposes, is commonly prepared from Carra- 
geen. The mucilage of carrageen is likewise much employed in the United 
States as a size for paper, cotton goods, felt and straw hats, and for thicken- 
* See two valuable communications by E. C. Stanford, in the ‘ Journal 
of the Society of Arts,’ for a detailed account of a new process for preparing 
iodine from kelp, and for a description of several other important products 
obtainable from Algz: and also a‘ Report on the Exhibits in the Paris 
Exhibition of 1878,’ by Paul, Holmes, and Passmore, in ‘ Pharmaceutical 
Journal,’ ser. iii. vol. ix. p. 303. 
