OF SOUTH AUSTRALIA. 
17 
strips and sold as agar. It is employed as a nutrient jelly in which to 
cultivate germs, bacteria, and fungi, in medical and bacteriological 
laboratories all over the world. 
Potash, Soda, Iodine. — In former days the alkaline carbonates were 
derived almost exclusively from plants. Potash was obtained by the 
lixiviation of the ash (Potashes) of the leaves, twigs, and rootlets of shrubs 
and trees. Soda was supplied by the treatment of Brown Seaweeds, 
especially the Fuci, reduced to ‘ 4 kelp” by imperfect combustion of the 
weed on the coast. So important was the industry during the time of the 
Napoleonic wars that fortunes were made. It is said that £400,000 per 
annum was paid for the kelp of the Hebrides alone. Then barilla, the 
impure ash of certain maritime land plants, Salsola, Salicornia, &c., was 
found to be richer in soda and was imported on a large scale from Spain, 
the Canaries, and other stations where the plant could be grown under 
supervision. But the discovery of the Le Blanc process, and later of the 
Solvay process, of manufacturing sodium carbonate from the cheap and 
omnipresent common salt, put an end to the employment of kelp and barilla 
alike. Sodium carbonate is no longer obtained from plant material. 
Almost all seaweeds absorb both potassium and sodium chlorides, but they 
vary greatly in their predilections. Some, as the Fuci , have a rich sodium 
content, but are poor in potassium, while the Laminariaceae have higher 
percentages of Potassium, so much as to render them a convenient source 
of potash salts. But here again the discovery of potassium salts in com- 
mercial quantities in the Stassfurt beds in Germany has ousted the plants. 
When the German prices became high the Americans conceived the idea 
of obtaining potash from their own resources, that the kelps might furnish 
all they wanted. Accordingly, they made a most detailed and elaborate 
survey of the extensive kelp beds along the whole coast of California, 
Oregon, and Alaska. Perhaps in view of this threat, German prices came 
down and the kelp scheme is for the present abandoned. But the Stassfurt 
accumulation cannot last for ever, and we may yet see the kelps established 
as an important source of alkali. 
Iodine is present in most seaweeds but in most of them in inappreciable 
quantities. That the weeds should be able to extract it at all is remarkable 
enough in itself, since the surrounding sea water contains normally 1 part 
of iodine in 260,000,000 parts of water. The Laminariaceae are among 
the richest, and factories are at work in Norway on species of Laminaria , 
while still more extensive are the factories in Japan, where other genera, 
such as Ecklonia , are also employed. In South Australia the Laminariaceae 
are represented by Ecklonia and Mocrocystis. A third genus, Lessonia , 
flourishes on the southern half of the coast of Tasmania. At my request, 
Mr. G. Ampt, of the Organic Chemistry Department of the University 
of Melbourne, made a complete analysis of samples of L. corrugata from 
the estuary of the Derwent. In the moisture-free material he found .176 
