84 REPORTS ON THE STATE OF SCIENCE.—1917. 
a sete pentosan—fucosan—which hydrolyses to form the methyl pentose 
—fucose. 
Trish moss grows extensively on the coasts of Ireland and Scotland, and 
was at one time largely used for sizing linen; it is still used to a limited 
extent. On soaking in water the plant breaks down to form a gelatinous 
mass, and on boiling with water it forms a colloidal sol which is quite fluid 
while hot, but sets to a gel on cooling. This material contains a con- 
siderable amount of finely divided cellular tissue and usually has a high 
mineral content, z.e., about 18 per cent. (H. B. Stocks and H. G. White, 
‘Jour. Soc. Chem. Ind.’ 1903, 4). Irish moss gel becomes less viscous 
with caustic soda; Ba(OH), and Fe,Cl, both yield precipitates and 
alcohol partly precipitates it. 
Agar-agar is a Japanese product derived from a seaweed ; it occurs in 
thin crinkled ribbons, and is extremely bulky, On heating with water it 
does not swell very appreciably or easily dissolve, but when solution is com- 
plete the liquid is very thin while hot, but on cooling it very quickly sets at 
about 50° C. to a solid brittle gel, which does not readily melt below the 
temperature of boiling water. These properties render it extremely useful 
for bacteriological investigations and other purposes. A solution con- 
taining only 1 per cent. of agar is quite solid at the ordinary temperature. 
Agar contains about 20 per cent. of moisture and only about 1 per cent. 
of mineral matter. It has no acid characters. I1t is only slightly acted 
upon when heated with caustic soda solution. Alcohol yields a white 
curdy precipitate, and it is also precipitated by basic lead acetate, and 
tannic acid, which latter does not affect Irish moss jelly. It mixes 
readily with gum arabic and hemicellulose solutions. 
Japanese isinglass is very similar to agar, sometimes being sold in the 
ribbon form and sometimes in rods about 1 in. square, which, however, 
consist merely of membranes filled with air bubbles, so that in this form itis 
equally bulky. 
It contains about 23 per cent. of moisture and 2-9 per cent. ot mineral 
matter, but likewise has a similar composition to agar (see also C. F. Cross, 
‘ Lectures on Cellulose’). It dissolves more easily and more completely in 
water than does agar, and on cooling forms even a stiffer gel. The gel is 
clear at first, but after a time it becomes opaque. It yields a white cloudy 
precipitate with alcohol and is precipitated by basic lead acetate. It mixes 
readily with gum arabic solution. 
Evaporated seaweed products in the form of scales are sold for sizing and 
finishing purposes under the names cf ‘ Algin,’ ‘ Blandola,’ “ Norgine,’ &c. 
Norgine is stated by E. Schmidt (‘ Chem. Zeit.’ 1910, 1,149-1,150) to be 
the sodium salt of laminaria acid. It is probably an adsorption com- 
pound, as are several of the products mentioned in the patents below. 
E. C. C. Stanford (Eng. Pat. 142, 1881, also 8,075, 1899; see also 
‘ Journ. Soc. Chem. Ind.’ 1886, 218) prepared a product (which he named 
‘ algin ’) by heating marine alge with caustic soda or sodium carbonate. 
The material was regarded by him as an acid, which he named “alginic 
acid’; this combined with alkalies to form soluble compounds—algenoids— 
which could be used for a variety of purposes, notably for sizing. By 
adding metallic salts such as those of iron, mercury, silver, &c., to the 
alkaline solutions, precipitates were obtained which he regarded as 
insoluble alginates, proposed to be used for medicinal and other purposes. 
Most of these were soluble in ammonia. The British Algin Co., T. Ingham 
