
- 
May 5, 1923] 
John Ellis, Ehret the botanical artist, Dr. John Mitchell, 
and others were among the earliest of his acquaintances 
in London. Then the scene shifts to Philadelphia, 
_ where he was often with Bartram: “he lives about five 
miles from Philadelphia, a thoroughly good fellow and a 
strong Linnean ; we have botanised a good deal round 
the country, and he has promised to send a quantity of 
rare seeds to Uppsala if he can manage to do so with the 
next ship.’”” Kalm then turned his steps to Canada, and 
returned to Pennsylvania at the end of the year, again 
reaching London in the spring of 1751, and Stockholm a 
month later, passing on to Abo ; in that University he 
had been appointed professor of economy, and on his 
return he took up the duties of his chair until his death 
in 1779, the year after the death of his old teacher.. 
There are but few letters here from Linnzus, the 
reason no doubt being that, the recipient having sewn 
these letters into a volume, they probably perished in 
the fire of 1827, which destroyed the town and Uni- 
versity of Abo. 
Martin Kahler (1728-1773), another of the Linnean 
pupils, had intended to travel to the Cape, but that 
intention was hindered by the Dutch. He therefore 
travelled in France and Italy, whence he returned in 
1757- Magnus Lagerstrém (1691-1759) was a director 
of the East India Company of Goteborg (Gottenburg), 
and in that capacity was able to supply novelties to 
Linneus ; thirteen letters are here printed, but the 
letters to Lagerstrém are unknown. The last writer 
in the volume is Erik Laxman (1737 ?-1796), whose 
name is well known for his work amongst Siberian 
plants. Baba 

Technology of Oils and Fats. 
Chemical Technology and Analysis of Oils, Fats, and 
_ Waxes. By Dr. J. Lewkowitsch. Sixth edition, 
entirely revised by George H. Warburton. (In 
3 vols.) Vol. 3. Pp. vili+508. (London: Mac- 
millan and Co., Ltd., 1923.) 36s. net. 
HE third and final volume of this well-known 
book deals principally with the technology of 
manufactured oils, fats, and waxes, as, for example, 
the refining of edible oils, the making of soap and 
candles, the purification of glycerine, oil hardening, 
and the preparation of polymerised, boiled, and 
oxidised oils. In appraising the value of these sections 
it must be remembered that the book deals essentially 
with the chemical aspect of these industries, and that in 
the few pages which can be spared to each it is im- 
possible to attempt more than a general outline of the 
processes in common practice. 
In particular, it is not part of the author’s scheme 
to indicate on the more mechanical side of the industry 
NO. 2792, VOL. I11 | 
NATURE 
ten pages to it. 
ae0 
which type of plant or process is at the moment gener- 
ally in use in an up-to-date factory. One consequence 
of this treatment is that the accounts of the manu- 
factures appear antiquated when read by one acquainted 
with practice, and the student of chemical technology 
trained on this book would justly be accused in the 
works of being too theoretical. On the other hand, it 
will be said there are numerous highly specialised text- 
books devoted to each of these subjects, and a brief 
summary of them from the more purely chemical 
point of view is quite enough to attempt. In this 
connexion it may be suggested that the book is rather 
overburdened with statistics. . 
An important section is that devoted to waste oils 
and fats: it may be defined as an essential function 
of the chemist in any industry to eliminate waste and 
to utilise the so-called waste products. In oil-refining, 
for example, much depends, from the economic point 
of view, on obtaining both a high yield of the refined 
product and the retention of the foots in a form in 
which they can be utilised. The respective values of 
soap stock, or soap stock fatty acids, often make all 
the difference in the refiner’s profit. Latterly anumber 
of alternative processes have been tried in this con- 
nexion, and some reference to them might well have 
been included in this volume. 
The subject of hydrogenated fats is dealt with very 
adequately in the well-known book of Carleton Ellis, 
so that the author may be excused for devoting only 
Of some interest is a paragraph re- 
ferring to the use of such fats in the edible-fat industry, 
particularly on the Continent, and indicating doubt 
as to their suitability. Actually to-day hardened fats, 
particularly whale oil, are the most popular materials 
for edible fats on the Continent, and the refiners are 
willing to pay a price for the raw oil which puts it 
beyond the reach of the soap-maker, at whose instance, 
it may be remembered, the hydrogenation process was 
invented. The refined product, which is absolutely 
free from nickel and of a high standard of purity, has 
many desirable qualities, though from the most modern 
point of view the absence of vitamins must be held 
to be a disadvantage. Very little hardened fat, how- 
ever, is used in margarine made in Britain. 
Probably no section of the industries based on oils 
and fats has developed more in this country than the 
manufacture of margarine, owing in the main to the 
abnormal conditions imposed during the War. The 
advance in the technology of this industry has been 
enormous, both in the methods of refining the crude 
fats, in their selection and blending, and in the actual 
manufacture of the margarine, including the bacterio- 
logical processes of imparting the special butter flavour. 
The new factories are models of their kind, and triumphs 
