200 Canadian Record of Science - 



form a useful addition to the means of thickening soups, etc., in the 

 kitchen. 3rd. By mixing -^ per cent, with the water supplied to 

 boilers, a calcium deposit is formed, which may be easily blown 

 off, thereby preventing troublesome incrustations. 4th. Mixed 

 with gelatine it may replace gum arabic in the manufacture of 

 lozenges and jujubes. 



Alginic acid may be separated from its sodium salt by means of 

 hydrochloric acid ; a little bleach will render it white, and it may 

 be separated by filtration and pressure and obtained in the form 

 of a cake, in which state it can be kept for any length of time in a 

 cool, dry place. 



Analysis of the alginates shows that the formula of the acid is 

 C 76 H 80 N 2 0, 2 which may be written thus : — 



NJ H 2 



lC 76 H 76 22 



as a diamide. 



It is a nitrogenous acid, extremely retentive of water, taking up 

 over 98 per cent, and it dries up to a horny substance resembling 

 albumen, with a s. g. of 1.534 (the s. g. of ivory nut is only 1.376) 

 in which state it can be turned and polished. It is easily obtained 

 in thin transparent sheets, which possess considerable tenacity 

 and in this form it is useful for tying over pots and jars. The sheets 

 may be readily coloured blue, red, &c, resembling the coloured 

 sheets of gelatine, but unlike them are not affected by water. Algi- 

 nic acid is a moderately strong acid, displacing carbonic acid from 

 the alkalies and earthy carbonates. The soluble alginates (sodium, 

 potassium, ammonium, lithium and magnesium) have all an acid 

 reaction. Some of the insoluble alginates are very soluble in am- 

 monia, with which they seem to form aouble salts. 



The aluminum alginate, for instance, is very soluble in ammonia, 

 but becomes when dried again insoluble, and forms a cheap water 

 varnish, and an efficient glaze for paper and cloth. It is quite 

 neutral. 



Shellac is dissolved by the alkaline alginates, the ammonium 

 solution, when evaporated, forming a thin, tenaceous film, quite 

 soluble in water, but which after being passed through a bath of 

 dilute hydrochloric acid is insoluble. The compound then resembles 

 sheet guttapercha, and it is thought might replace that substance 

 for surgical dressings. Eemembering the great brittleness of shel- 

 lac, which destroys its value for many purposes, no one would sus- 

 pect its presence in s'ch quantity in this very pliable sheet. 



Many other resinous bodies may also be incorporated in a simi- 

 lar manner with a soluble alginate and then rendered insoluble- 



Alginic acid also combines with many alkaloids, forming soluble 

 films, some of which may be usefsl in medicine, but none have as 

 yet been fully investigated. Compounds have been obtained and 

 exhibited by Mr. Stanford of alginic acid with quinine, chinoleine 

 &c, about which he promises further reports. — Journal Soc. Chem. 

 Industry. 



