OcTOBER 30, 1902} 
Now that the war is over, cannot some appeal be made to 
remedy this state of things? Is it too much to hope that a chair 
for ethnology might be endowed by private benefaction for the 
new teaching University of London, or at least that subscrip- 
tions might be secured sufficient to place the existing lectureships 
in Cambridge on a sounder and more satisfactory basis ? 
ANTHROPOTAMIST. 
Phosphorus versus Lime in Plant Ash. 
TuAT in the mineral constituents of leaves a_ strong propor- 
tion of lime is an obstacle to the presence of a considerable 
quantity of potass has been recognised as a feature of calci- 
fugous species of plants. It has been sought, indeed, to explain, 
apparently on this ground alone, the existence of special plants 
which shun lime soils, or at least to account for the difference 
between their habitat and that of calcicolous species. A certain 
proportion of lime in the soil, say about 12 per cent. carbonate, 
is sufficient for the needs of a certain number of calcicolous 
species and banishes the calcifugous species from it. ‘If, how- 
ever, we carefully examine the ash constituents of the leaves of 
herbs growing and seeding in a soil (such as here in this valley) 
with only about 1 per cent. lime (CaO) in its finer particles, we 
recognise a large ratio both of potass and of lime, as the 
annexed table will attest. 
Constituents of the 
Ash 
Per 
Leaves of Date. ape tb 
Pel Sea CEO, | P30s. 
Hawkweed ............--- July 15 | 12°6 | 24°7 | 28-4 | 4°3 
SENN WOY Bits. cauceantes to===- es 24: 8-9 |.31°7 | 24°7 | 8°35 
Bracken (stem) ......... ae — 638 4°I | 3°04 
Cranesbill (lamina) a or Yes |\ ai} |) 2a ES 
MPEVENWeensactndeeer snore ss ne 6°3 | 18 Bom || 757 
RRO WAN Geemacdecrcatesie ce. a2 53, 3h NG 38°5 | 23 56 
IDYove) | incnenccBeCOnCORBEEEE jAug. I.) Ene) Ag Aie2o. | 6°3 
Wate aerate, >< +ds ri ome S; 8°7 | 42°2 | 29 6 
MSVEAIIOLE adap aeccs) a «3% iy) SIAN EORR egsrOmbe5c7> |. 4°7 
Great Knapweed......... > DEZi| £O 37°T |,29074 | 3°6 
PRA OU OE a cleniciae iad = 0 «3 jr Gn) Les2meaaeseese7: |, Sf I5 
LNfovige! S172) ee ee aa 211 OE A Onzanlie25 73 5135 
Heather(whole plant)... |Sept. 19 | 2°2 | 25 Forze 753 
Sycamore fruit............ iiss, 2401 555 eea 25-7 | 8 
These figures are taken from my own analyses, the percentages 
being calculated on the crude ash minus charcoal. The sphere 
of experimental observation is, perhaps, too narrow or restricted, 
but a suspicion is awakened by the results that the need for phos- 
phorus is a direct or indirect agent operative in the case. That 
is to say, a strong proportion of lime in the ash seems rather an 
auxiliary or accompaniment than an obstacle to a strong pro- 
portion of potass (as computed by the soluble salts). On the 
other hand, we see a rough approximation to an inverse ratio 
between the lime and the phosphorus, z.e. roughly 28 or 29 per 
cent. of lime with 3 or 4 P,O;, and 23 or 24 lime with § or 9 
P.O, ; and where this does not prevail, the whole percentage of 
ash is below the average (as in water flag and the woody plants). 
That a poor yield of certain plants on calcareous soils appears to 
be due to the effect of the lime in preventing the assimilation of 
phosphorus is a result of the experiments of MM. Dehérain and 
Demoussy. Moreover, it is known that the ash of seeds, which 
is invariably very rich in phosphorus, contains also a compara- 
tively very small proportion of lime. It would seem, therefore, 
to be legitimate to conclude that a certain proportion of lime in 
the soil (say 3 or 4 per cent.) is inimical to the life of certain 
plants which require a definite amount of phosphoric acid for 
the healthy performance of their physiological functions. The 
fact that some plants will grow, but not flourish or propagate, in 
certain localities or habitats is a pretty certain indication that a 
sufficient amount of phosphorus is not available to the seed for 
purposes of germination and development. The analyses would 
seem to indicate that a too liberal supply of lime is the preventa- 
tive agent in the case. P, Q. KEEGAN. 
Patterdale, Westmorland. 
NO. 1722, VOL. 66] 
-NATURE 
655 
ALUMINIUM AND ITS ALLOYS. 
HE electrolytic process for the extraction of 
P aluminium, which was patented in 1887 by Héroult 
in Europe and by Hall in America, has resulted in such 
a great diminution in the cost of production that the 
price of the metal has fallen from about twenty shillings 
to one shilling a pound. It is not surprising that, in the 
early days of the electrolytic industry, this circumstance, 
combined with the many very valuable properties of 
a, caused extravagant hopes for its future to be 
raised. 
The experience that has been gained in the past five 
or ten years has enabled us to form a truer estimate of 
the value of the metal, though it would be difficult to say 
even now to how great an industrial importance it may 
ultimately develop. A very good idea of the present 
position and prospects of the industry may be obtained 
from two papers recently published in the /owrnal of the 
Institution of Electrical Engineers. The first of these, 
by Prof. E. Wilson, gives the results of an elaborate 
series of tests of the physical properties of a number of 
aluminium alloys; we shall have occasion to refer to 
this paper later. The second paper is by Mr. W. Murray 
Morrison, and contains a description of the British 
Aluminium Company’s works at Foyers and an account 
of the applications of the metal, its use as an electrical 
conductor being considered at some length. We are 
enabled by the courtesy of the British Aluminium 
Company to give an illustration showing the turbo- 
generators in the power-house at Foyers. 
The Hall and Héroult processes for the electrolytic ex- 
traction of aluminium are practically identical and are too 
well known to need lengthy description. The aluminium 
is obtained as the result of the electrolysis of alumina 
dissolved in melted cryolite (6NaF.Al,F,). The electro- 
lysis is carried out in a carbon-lined crucible, at the 
bottom of which the separated metal collects, the 
liberated oxygen combining with the carbon of the anode 
and passing off ultimately as carbon dioxide. It is in- 
teresting to note that, whereas the specific gravity of 
solid aluminium is less than that of solid cryolite, in the 
fused condition this order is reversed ; but for this the 
process in its present form would be unworkable. Some 
figures showing the cost of production by the Héroult 
process are given by Mr. Blount in his “ Practical 
Electrochemistry,” as follows :— 
Cost of power 2°2 pence per Ib. of aluminium. 
Cost of alumina 4°0 ” ” »” 
Cost of electrodes 2°0 99 ”» ” 
Cost of labour, &c.... 2°0 95 ” ” 
Total cost LOL 
” ” ” 
It is probable that this estimate is somewhat high, but 
it is sufficient to show that the cost of power is a very 
important item, which explains the necessity for the use 
of water-power. The cost of power per lb. is higher 
than in any other electrolytic manufacture ; it forms, it 
will be seen, about one-fifth of the total cost; in the 
manufacture of calcium carbide, another electrochemical 
industry requiring cheap power, the ratio of cost of 
power to total cost is about I to 7°5. 
The product of the electrolytic furnace is very pure. 
According to Mr. Morrison, commercial aluminium is 99°5 
to 99°6 per cent. pure, the impurities being iron (about 
o'25 per cent.) and silicon (about 0°17 per cent.). A 
sample of pure commercial aluminium analysed by Prof. 
Wilson contained 0°31 per cent. Fe and o'r per cent. Si, 
which agrees pretty closely with Mr. Morrison’s figures. 
1“*The Physical Properties “of certain Aluminium Alloys, and some 
Notes on Aluminium Conductors,” by Prof. E. Wilson. (Journal I.E.E., 
vol. xxxi. p. 321.) ‘*‘ Aluminium: Notes on its Production, Properties and 
Use,”’ by W. Murray Morrison. (/éid. p. 400.) : 4 
