THE CHEMICAL NEWS,

VOL. CXXXII. No. 3443.

MERTON HOUSE, SALISBURY SQUARE, LONDON, E.C.4. TELEPHONES : Administrative: Central 6521. Printing Works: Hop 2404.

LIPIN AND THE LIPIN THEORY.

By JOHN MISSENDEN, B.Sc.

So far as research has gone, it seems probable that the lipin to which the writer has referred to previously' is, or at least has the nature of, a lipoclastic enzyme; and because of this, catalysts in chemical interchange (as in the case of its own hydrogenation) are entirely unnecessary. It has been found somewhat difficult to isolate a good specimen (although lipin is believed to exist in all animal tissue), but that contained in the liver will be found to answer to many of the reactions indicated by the manifestations of odour. It must be remembered, in considering whether a lipin reaction with an odiferous substance results in violent or mild chemical change, that what takes place in the beaker might not take place in the nasal passages. Nevertheless, the hypothesis that beaker and nasal membranes exhibit the same or nearly the same actional qualities is based upon such a wide and satisfactory series of tests that it may be taken for granted with safety.

a

Present knowledge of the constitution of nasal lipin is conflicting, and by no means complete. Nevertheless, it is generally agreed that it originates on the more exposed living cells-possibly as a by-product of their protoplasm-and that it has definite function in regulating the "lifeelement of those cells. Its influence seems to be twofold; to provide a protective surface for each cell, and to be sufficiently versatile in its properties as to provide each cell with a means of sensation.

Here the phenomena of smell is satisfactorily explained. Minute particles of a substance are taken into the nose and react with lipin. At once the molecular disturbances in the lipin are communicated to the living cell, and so smell is experienced.

It appears that, wide in its application as this table is, there appears to be at least one exception to the generalisation it advances farnesol, a sesquiterpene alcohol of group formula (CH3),C: CH.CH2.CH2. C(CH): CH.CH.CH2.C(CH,) : CH.CÍ, OH. However, the table is a most handy guide for the field it covers.

The observations made by Durrans do not show any complete connection between molecular weight and odour, or between molecular potency, molecular distribution, and odour; but the table itself does demonstrate one very important rule; namely that, so far as the groups enumerated are concerned, molecular weight definitely controls limits at which odour is possible. It will be found more generally that the molecular weights of bodies capable of odour lie between 16 and 312, irrespective of whether they are organic or inorganic. But molecular weight has no apparent bearing upon quality of odour, as substances of almost the same molecular weight have widely different odours altogether, as in the case of geraniol and vanillin (152.178 and 152.104 respectively).

MOLECULAR FORCE.

Here one is bound to accept the theory of Teudt (Chem. Zent., 1919, 6. 138), coupled with the discussion of Durrans and Tschirch (J. Chem. Soc., 1921, Abstracts I., p. 775). Durrans and Tschirch support the contention that odour is solely due to chemical reaction on the nasal membranes, and Teudt (whose work in this connection has been somewhat severely criticised by Heller (Amer. Perfumer, 1920, 365), states that odour springs from a condition of electrionic vibration. Collating the two arguments, it would certainly appear that odour is a condition of molecular force-a matter of valency and rate of chemical interchange. Thus the study of odour conditions lies in three separate directions, each of which is necessary to bring the subject within the range of accurate computation:

(1) The exact chemical constitution of the particular lipin associated with olfactory nerve-endings;

(2) The electronic forces which operate between lipin and all oriferous substances, and the rates at which they operate; and

(3) Matters which involve the phenomena. of volatility.

It is the first two of these which form the basis of the Lipin Theory.

The writer would refer to his former paper in the Chemical News, 1923.

THE SCIENCE OF STEAM
GENERATION.

SOME STRIKING TESTS AT THE CENTRAL
ELECTRIC SUPPLY COMPANY, LONDON.

By A WELL-KNOWN ENGINEER. During the past few years steam generation, so far as large water tube boilers are concerned, has become an exact science, with continuous flue gas, as well as fuel, analysis, and complete pyrometric control in a manner hardly approached by any other furnace operation. The rapid progress made is well illustrated by the results of a series of remarkable 8-hour tests that have just recently been carried out at the Central Electric Supply Company's power station, St. John's Wood, London. These

show an average of about 85% efficiency with mechanical stoking and coal of approximately 10,000 B.Th. U. per lb., all the more noteworthy when it is borne in mind

fin water-cooled tubes "Murray-Usco " are not fitted, which would bring the results up to over 90%.

The plant under official test consisted of a "Babcock & Wilcox " water tube boiler, 200 lbs. pressure and 625° F. superheated steam temperature with a heating surface of 8,619 square feet and a superheater of 3,190 square feet, while the accessory equipment includes a "Green" economiser of 4,620 square feet and "Usco" air heater of 9,130 square feet, with 110 thin metal plates, electric welded in the outer casing to give 1 inch spaces, the normal evaporation of the plant as tested being 60,000 lbs. of water evaporated per hour.

The boiler is fired by three "Underfeed Class A " travelling grate forced draught stokers, installed by the Underfeed Stoker Co., Ltd., of London, giving a total of 308 square feet grate area, while the forced and induced fans are of the "Sirocco " type, by Messrs. Davidson & Co., Ltd., of Belfast. Finally, the coal used was Scotch Washed Peas, containing 15.85% moisture, with 10,379 B.Th. U. per lb., according to the lower or nett heating value, and Stanley slack, having 10.31% moisture and 10,000 B.Th.U., a low-grade quality.

The efficiency figures given in great detail are complicated as usual by considerations of nett and gross heating value of the fuel, but the average efficiency varied from 83.2% to 85.8% calculated on the gross or heating value of the coal without deducting the auxiliary power used. If the latter is taken into account as regards the power used for the fans and stoker, the actual nett efficiency is 82.4% to 85.1%, while if the lower or calculated so-called nett heating value is assumed the figures are 85.6% to 88.4% with the deduction of the auxiliary power, or 86.4% to 89.2% without. The amount of air used per lb. of fuel was 12.45 lbs., as compared with the theoretical figure of 8.50 lbs., an excellent performance, while the water evaporated per lb. of coal as fired was 7.94 lbs., corresponding to 9.83 lbs. from and at 212° F.

Some further detailed figures of the tests are that the CO, average 11.1 to 12.4%, while the temperature of the gases leaving the boiler varied from 525 to 540° F., and the feed-water economiser raised the temperature from 165-170° to250-270° F. The average temperature of the air entering the air heater was 103-107° F., subsequently delivered to the stoker at 237-245° F., with an average velocity of about 535-629 feet

By GEORGE ROGERS MANSFIELD AND
LEONA BOARDMAN.

(U.S.A. Bureau of Mines.)

The year 1924 was marked by continued low-price levels for foreign potash and was particularly noteworthy because of the signing in August of the Franco-German potash agreement, which virtually re-established the German-Alsatian potash monopoly. The American industry, however, not only held the place it had gained during the previous year, but made substantial gains. This was largely due to the work of the American Trona Corporation, which was the principal producer.

The number of plants reporting potash production in the United States was 11, one less than in 1922 and 1923.

A comparison of the figures for 1924 with those for 1918, when domestic production was at its height, shows that in 1918 the crude potash production was over four and one-half times as great as in 1924, whereas the available potash (KO) content of the material produced in that year was only about two and one-half times that for 1924.

In 1913, the last normal year before the war, the United States imported 270,720 short tons of K,O. In 1924 the total im[ports were 200,365 tons, or 74 per cent. of that amount. This was 9,585 tons, or 4.6 per cent. less than the imports in 1923, but practically the same as the imports in

1922.

RECOMMENDED SPECIFICATION FOR QUICKLIME AND HYDRATED LIME FOR USE IN THE PURIFICATION OF WATER.

In the treatment of water for public supplies lime is used alone or with iron sulphate or aluminium sulphate to produce a precipitate which assists in the clarification of the water and in the removal of bacteria by filtration. Lime is used sometimes to partially soften the water. Lime and soda ash are used together for softening water. Quicklime is generally used in municipal plants and hydrated lime in smaller plants. For these purposes quicklime should contain at least 90 per cent. available lime and hydrated lime at least 90 per cent available calcium hydroxide.

DEFINITION OF LIME.

Quicklime is the product resulting from the calcination of limestone. It will slake when water is added to it, and this slaking is accompanied by an evolution of heat, and increase in volume, and the formation of calcium hydroxide. Hydrated lime is a dry powder which is made by treating quicklime with enough water to satisfy its chemical affinity.

USE OF LIME IN WATER PURIFICATION.

In the treatment of water for public supplies lime is used alone or with iron sulphate or aluminium sulphate to produce a precipitate which assists in the clarification of the water and in the removal of bacteria by filtration. Lime is used sometimes to partially soften the water.

Lime and soda ash are used together for softening water. Quicklime is generally used in municipal purification plants and hydrated lime in smaller softening plants.

QUALITY.

The constituents other than calcium oxide ordinarily found in lime, and which include underburned and over burned lime, retard the slaking process. The presence of any inert material will thus introduce delays which reduce the efficiency of the equipment.

PACKING.

Quicklime is shipped in bulk in carload lots or in wooden barrels or metal drums holding 180 pounds. Hydrated lime is shiped in paper bags holding 40 or 50 pounds net each.