USEFUL ALGAE — CHASE 439 



until World War I. Stanford was engaged in the Scotch kelp in- 

 dustry when he noticed that one of the brown kelps, Lamin/zria digi- 

 tata (pi. 6, fig. 1) after exposure to rain assumed a tumid appearance 

 and that sacs of fluid were formed from endosmosis of the water 

 through the membrane, dissolving a peculiar glutinous principle. 

 Wlien the sacs were cut, a neutral, glairy, colorless fluid escaped. It 

 could often be seen partially evaporated on the frond as a colorless 

 jelly. This substance, insoluble in water, was given by him the name 

 of algin. He found that algin contained calcium, magnesium, and 

 sodium in combination with a new acid called alginic acid. When 

 this natural liquid is evaporated to dryness, it becomes insoluble in 

 water but very soluble in alkalies. This substance is so abundant in 

 the seaweed that on maceration for 24 hours in sodium carbonate in 

 the cold the seaweed plant is completely disintegrated. He found 

 that it had an extraordinary gelling power. It has 14 times the vis- 

 cosity of starch, and 37 times that of gum arable. It does not co- 

 agulate with heat. 



The commercial product is now in the form of a white powder pro- 

 duced from kelp found in Ireland, Scotland, Norway, France, and on 

 the Pacific coast of the United States. Laminaria hypohorea is used 

 for the production of algin in Ireland and Scotland, and Macrocystis 

 pyrifera (pi. 7, fig. 1) is employed in the United States. Its Eng- 

 lish trade name is Manucol. Manucol solutions are stable in the 

 pH range 5.5 to 8.5 and may be pasteurized at 50° C. without affecting 

 the grade. It is useful for cosmetic preparations having an aqueous 

 or glycerine base such as glycerine hand jellies, transparent setting 

 lotions, shaving creams, and beauty milks. It is used in sunburn 

 lotions and in hair creams and fixatives. 



Its value in the cosmetic industry lies in the fact that sodium 

 alginate produces standard mucilages that do not vary much pro- 

 viding the conditions of their preparation are similar. These mu- 

 cilages are transparent, water white, and almost odorless, thus over- 

 coming the difficulty caused by the use of certain Karaya gums which 

 have a grayish-brown color and also avoiding the question of opacity 

 which arises with the use of tragacanth. The viscosity of Manucol 

 V solutions is raised enormously by the introduction of calcium ions 

 and if sufficiently raised the solution gels. The thickening effect of 

 calcium ions increases as the pH of the solution is lowered due to the 

 precipitation of calcium alginate as a jelly from the soluble alginate. 

 All metallic ions other than those of the alkalies, magnesium, and 

 ammonium behave similarly. The interesting feature about alginates 

 is that it is possible to vary the viscosity of the solution over an 

 infinitely wide range merely by altering the proportion of the calcium 

 or other ion. 



