Ac«isT 9, 1913. 
THE GARDENERS* MAGAZINE. 
605 
i PARTIAL STERILISATION OF | 
❖ 5;nii^ f 
(Continued from page 578.) 
Partial Sterilisation by Chemi¬ 
cal Methods.—The Use of 
Antiseptics. 
In out earlier experiments we con- 
fiiwd ourselves to two antiseptics that 
happened to be very convenient for our own 
purpose. The experiments have since been 
extended to include a number of other anti¬ 
septics belonging to six different classes, so 
as to ascertain how wide a choice would be 
open to the horticulturist. The groups 
tested weire:—1. Volatile hydrocarbons: 
toluol, light solvent naphtha, benzene, 
petrol, etc.; 2. Heavy hydrocarbons and 
their derivatives: naphthalene, etc.; 3. Tar 
acids: carbolic acid, cresylic acid or cresol, 
etc.; 4. Tar bases: pyridene and the higher 
bases, lutidene, collidene; 5. Formaldehyde; 
6 . Inorganic antiseptics: calcium sulphide. 
The substances in the first group, the 
Tolatile hydrocarbons, gave good results in 
our glasshouse, but proved very troublesome 
when we came to use them in commercial 
nurseries. There was great difficulty in ap¬ 
plying them to the soil: a hand injector 
Moved too laborious, and spraying too waste¬ 
ful; further, they had little action in wet 
•oil by reason of their insoluble nature. An¬ 
other objection of a wholly different kind, 
but no less serious, was the trouble about 
carriage, railway companies declining to 
carry them except in special packages con- 
fora ing to the Railway Clearing House spe- 
jwation and at a minimum charge of 5s. 
ki water transport was avail- 
wle the charges were less, but the material 
was a long time in reaching its destination, 
nese difficulties may be overcome in time, 
W for the present they put out of the 
nge of p^ctice all the volatile hydrocar- 
8 , and the other volatile substances, such 
disulphide and ether, 
b group, the heavy hydrocarbons, 
nanVifl includes heavy solvent 
du?f« its reduction pro- 
tainp^ other of the waste products ob- 
thabn«^\! • j and refining of naph- 
taiivpd ’ ^®^des certain other substances ob- 
have these waste products 
^ special treatment 
tor is iLf / purely hydrocarbon charac- 
oal defiTii'i-- ^ ^ rigid chemi- 
^acts Of these pro- 
*<«•« “ solid, and is tfere- 
hand* and applied; on the 
*®d hen<v» A dissolve in water, 
cold^ii^^! readily spread about in 
iuicklVoi, volatile, 
change into vapour and do 
cucumber La ^ temperature of a 
to w • .other products are 
ordinarv^^”^ uon-inflammable, require 
carried af transport, and are 
jnjulsifyg^ dinary rates; some mix or 
^ Watered ^^^t they can 
Wthers inf with the greatest 
Wn mil^ emulsify until they 
3 ^ substance. 
^'«‘ttfectant being able to water in the 
easily emulsifi^Kf^^ soluble 
substances are likely 
®*&lit he snL distributed in the soil 
bv tK^^i of them are ab- 
so solutions or 
L to travel into 
^ the It, top two or three 
and thri “^oh anti- 
depths penetrates to 
?aT;“t of^the a^tL^K insufficient 
S* purpose. TV ^ to serve any use- 
soils and^in^^lf^ marked in 
and in those containing much 
organic matter derived from turf or stable 
manure. 
The tar acids, which form our third gioup, 
are already used in glasshouses as disinfec¬ 
tants. At least four occur in the well- 
known “ straw-coloured carbolic —phenol 
and the three cresols—but we have no in¬ 
formation as to whether any one of the four 
is more useful than the rest. The acids are 
effective, but they do not dissolve or emul¬ 
sify to a sufficient extent in cold water, 
although they dissolve more easily if soft 
soap is added, and are completely soluble in 
warm water. They also are abstracted from 
their emulsions by soil, so that they do not 
readily penetrate to a great depth. 
The tar bases have the advantage of sup¬ 
plying some plant food as well as partially 
sterilising the soil, and their nitrogen rapidly 
becomes available for the plant. They have 
a very powerful odour, which may, indeed, 
prove tw much for tW horticulturist, but 
they can be converted into less odorous solid 
salts, with which, however, we have not ex¬ 
perimented. 
Formaldehyde has the advantage of being 
volatile, so that it spreads readily in the 
soil without being absorbed locally like 
some of the substances mentioned above. It 
has proved the most effective antiseptic we 
have tried. In the pure state it is a gas 
at ordinary temperatures, but it readily 
condenses, and is sold as a 40 per cent, solu¬ 
tion in water. Sometimes the solution is 
called Formalin, but this name is the pro¬ 
perty of a particular German firm, and their 
brand has to be supplied whenever formalin 
is asked for; “40 per cent. Formaldehyde,’' 
however, is not a proprietary article, and 
can be manufacture and sold by anyone. 
It has an irritating smell, but does no injury 
to the men if properly used. 
Of the inorganic antiseptics we have as yet 
only used calcium sulphide. This nroved 
very effective, and, moreover, it changes 
afte its work is done into useful calcium 
carbonate. It is not at present obtainable on 
a large scale. It used to constitute the old- 
fashioned gas-lime, the so-called “ Blue 
Billy,” but only small amounts are found in 
the gas-lime commonly sold at the present 
day, owing to recent changes in the method 
of gas purification. 
The group is, however, very large, and 
contains many other substances, some of 
which such as sulphur and boracic acid, 
have been recently tried by other investiga¬ 
tors with results said to be satisfactory. 
Lime in sufficient doses has been found very 
good. Bleaching powder also appears to be 
promising. 
Some objections may be found to all the 
substances in these groups. The first group 
is readily distributed in the soil, but is 
highly inconvenient in practice with out pre¬ 
sent methods; the second and third groups 
are very convenient to handle, but are apt 
to distribute badly in the soil owing to local 
absorption; the fourth group has a bad 
odour, but otherwiS§ answers well; formalde¬ 
hyde at the present moment is expensive 
(7d. per lb.), although there seems no reason 
why its price should remain high if it were 
inade on a larger scale. We have not yet 
met with the ideal combination of qualities 
in any one substance, and the grower’s choice 
must be determined by three considerations 
—effectiveness, convenience, and price. 
The effectiveness of an antiseptic varies 
with the conditions under which it is used, 
so that it is impossible to set out a number 
of substances in any rigid order of merit. 
Only a rough grouping into classes can be 
attempted, and it must be realised that a 
different method of application would cause 
a certain amount of readjustment in the 
classification. During the present season’s 
work the antiseptics have come out in the 
following groups: — 
1 st Group, most effective.—Formaldehyde, 
pyridene, the higher bases, collidene, luti¬ 
dene, etc. 
2nd Group, less effective.—Benzene, cal¬ 
cium sulphide, carbolic acid, cresylic acids 
(i.e., cresols), light solvent naphtha, heavy 
solvent naphtha, petrol, toluol. 
3rd Group, still less effective.—Nanhtha- 
lene and certain derivatives obtained during 
its preparation, nitrobenzene. 
The order within the groups is alphabe¬ 
tical only. These groups are based on the 
effects observed on our tomato plants and 
the fruit picked up to the middle of July, 
but later on certain other effects appear^ 
which would cause some of the third group 
to be moved up into the second, and vice 
versa. On the whole, however, the early 
effects and the early fruit are the more im 
portant, and we therefore prefer to leave the 
list as it stands. 
None of these substances are as effective 
as heat, but several are much superior to 
toluol, the best agent we knew last year. 
This fact encourages the hope that we may 
yet find even more useful substances than 
those in our present first group. 
The relative convenience of working with 
these various substances can only be ascer¬ 
tained by large-scale experiments in commer¬ 
cial glasshouses. Three kinds of application 
are involved: applications of volatile sub¬ 
stances, of solutions or emulsions, and of 
solids, but there seems no reason why any 
of these should prove beyond the power of 
the horticulturist. 
The question of price is naturally one 
about which no general statement can be 
made. Some of the above substances are by¬ 
products and not much in demand; at the 
moment their price may be low, but it is 
liable to increase once tlie demand increases. 
Others are definitely manufactured and put 
on the market, but usually for some special 
purpose requiring more or less costly treat¬ 
ment unnecessary for horticultural use. How 
little the current price of a substance likely 
to be used in agriculture or horticulture is 
an index of its future price is shown by the 
history of superphosphate; prior to the time 
of the first artificial manure factory super¬ 
phosphate was simply a chemical curiosity 
unobtainable on the market in any quantity. 
For this reason we have taken no account of 
current prices in making our choice of anti¬ 
septics for trial, but have included any sub¬ 
stance that seemed likely to be producible 
cheaply. Many waste products are cheap, 
but they are very variable in composition 
and no uniformity is guaranteed; our ex¬ 
perience is that for the present purpose they 
cannot be recommended until they have been 
examined carefully and the behaviour of 
their separate constituents is known. In 
practice this necessitates a certain amount 
of manufacturing and standardisation, which 
becomes a factor in determining the final 
price. Only actual trial avails to determine 
what is and what is not a useful antiseptic; 
remarkable actions go on in the soil, ren¬ 
dering innocuous substances which a priori 
might be supposed to be very injurious. 
Pot Vines intended for forcing next 
spring should now be ripening, and will 
require increased ventilation and less mois¬ 
ture; watering must be gradually reduced 
as ripening proceeds. Liberal fe^ng and 
good syringing ought to be supplied until 
the foliage changes colour, in order to keep 
the leaves clean and healthy, without whicli 
good buds cannot be expect^.—F. Jordan. 
The Double-flowered 
Bramble. — The dressed garden is 
scarcely the place for this, but in the wilder 
parts it forms a very pleasing feature when 
m bloom. Even on dry hanks, where but 
few flowering shrubs will hold their own, it 
will both grow and flower well. The blos¬ 
soms, which are-closely packed with petals, 
are not unlike double pink daisies. There is 
also a double white variety, but the pink is 
the more pleasing.— 
