SCIENCE AND INDUSTRY. 
a mean temperature. A Swiss engineer, Zuppinger, has designed a 
furnace in which, when the outside temperature is relatively low, the 
fire-space can be reduced by means of detachable walls and so save 
15-25 per cent.-of fuel. This type has also been tested at the Berlin 
Technical College, but no results are available. 
TURPENTINE AND ROSIN: NEW INDIAN SOURCE. 
“ Boswellia serrata” is a tree of the Burseracee order growing in 
India, which in Gwalior has been tapped by the natives for generations 
for its resin. Its possibilities have been investigated recently by the 
Indian Forest Service, who estimate that the cost of collecting the 
resin is about 9s. per cwt., and that the annual output should exceed 
27,000,000 Ibs. in India. An experimental distilling plant set up at 
the Forest. Research Institute produced from the resin turpentine oil, 
rosin, and gum. The turpentine oil is of very good quality, closely 
resembling American; varnish made from it is rather duller than that 
from American oil, but quicker drying. The rosin is also satisfactory, 
and was valued at from £20 to £22 per ton in London. The gum, 
however, is of doubtful value, being poorer than gum arabic, and if 
put on the market at all it should be as flour, to allow of admixtures 
to increase the viscosity. The conclusion is that the exploitation of 
“ Boswellia serrata ” should be a valuable commercial asset to India. 
_ POTASH FROM KELP IN CALIFORNIA.’ 
In the Journal of Industrial and Engineering Chemistry 1919, 
x1., 864, Messrs. J. W. Turrentine and Paul S. Shoaff describe the 
experimental plant of the United States Department of Agriculture 
at Summerland, California. Kelp is collected by boats of 100 to 150 
tons capacity, provided with twin screws and driven by internal com- 
bustion engines. The extreme bow of the boat is provided with the 
harvesting apparatus, the kelp is cut by means of knives approximately 
4 feet below the surface of the water, and is then carried to the deck 
by a conveyor; from 25 to 50 tons are harvested in an hour. The 
cargo is removed from the boat by an automatic fork, which delivers 
its load to the hopper of a chopper on the deck. The chopper cuts 
the kelp into lengths of approximately 6 feet, which are then moved 
to the storage bin of the plant by drag conveyors. The raw kelp is 
fed into a rotary drying kiln, where it meets a counter current of hot 
air, which enters the kiln at a temperature of 800° G. and leaves it at 
a temperature of 50°C. This preliminary drying is followed by a 
final drying in a similar kiln. The dried kelp is fed into the top of a 
retort, which is kept at a temperature of approximately 980°C. The 
charred mass is drawn off from a hopper at the bottom of a. retort, 
cooled, ground, and lixiviated. The by-products are recovered. In the 
- lixiviation use is made of leaching troughs, filter presses, and the prin- 
ciple of the counter current. The char is first extracted with a -concen- 
trated brine, while fresh hot water is used for its final extraction. The 
press coke of charcoal is extracted successively with hot hydrochloric. 
acid and water; by proper extraction a product is obtained which is of 
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