580 
THE GARDENING WORLD 
May 9, 1896. 
finish, which takes effect at a reduced graduated 
point of temperature, and, while the automatic 
discharge, seriatim, of waste vaporous matter is 
effectually provided for, we likewise ensure a suc¬ 
cession of currents of fresh dry, hot air, which 
automatically pass underneath, diagonally through, 
and then off, over the trays inside the inclined auto¬ 
matic flue.” 
The currents of hot air passing through this 
evaporator, when in full work, are said to be " self- 
created and continuous, strike the trays at a uniform 
upward angle with considerable velocity, quickly 
absorb all moisture, then pass off out of the 
evaporator.” The “American” is made in a number 
of sizes ; the smallest No. o, is made for family use 
or limited operations only, and costs £ 6 ios. to 
£8 15s., according to the number of sets of trays 
required ; No. 1 has a surface drying capacity of 35 
square feet, and the price is £13 to £17. 
No. 2 is of rather more than double the capacity of 
No. 1 ; price, /19 ios. to £26. The evaporators of a 
larger size are called “ commercial sizes.” Of these, 
No. 3 has a drying capacity of 300 square feet, and is 
capable of drying from forty to fifty bushels of Apples 
daily; the price is £52 to £ 7 o. Still larger sizes are 
made when required. All through this paper a day 
may be taken to mean twenty-four hours, as when an 
evaporator is set to work in the States it is usually 
kept going night and day. Except the furnace fit¬ 
tings, the “ American ” evaporators are chiefly made 
of wood, which the makers claim to be the best sub¬ 
stance for the purpose, and it is stated that the 
insurance record shows that they are quite safe 
from injury by fire under ordinary circumstances. 
The evaporator is the kind best known in England, 
and a number are in use in different parts of the 
country. One of them is on the estate of Mr. 
Ricardo, Bromsberrow, Ledbury. This gentleman's 
gardener, Mr. W, Trotter, has become a most expert 
evaporator of fruit, vegetables, herbs, &c. Later on 
I shall have the pleasure of reading to you some 
notes of Mr. Trotter’s experiences, and his opinion 
of the value of the apparatus. 
The " American ” evaporator has been exhibited 
at several agricultural shows, including that of the 
Royal Agricultural Society at Nottingham, in 1881 ; 
and again at the Windsor jubilee Show, in 1889, 
where it was awarded the society's prize of £7,0. 
The size which won this prize was the No. 2 evapora¬ 
tor, and is the one I consider most suitable for 
average requirements. In vol. 1, pp. 494-6, of the 
Royal Agricultural Society's Journal (1889), there is 
a most favourable report on the trial made at 
Windsor, where the judges appear to have been 
quite satisfied with the performance of this kind of 
evaporator. 
One of these No. 2 " American” evaporators was 
presented to our Royal Horticultural Society through 
the influence of Mr. Ludwig, and has been fixed in 
their gardens near Turnham-green since 1891. Some 
public and successful demonstrations of its useful¬ 
ness have been made, and one which took place in 
July, 1891, and which I will presently describe, was 
attended by a large number of influential gentlemen 
interested in horticulture and particularly in fruit 
growing. 
It has always seemed strange to me that the 
publicity given by these demonstrations, and the 
many letters which have appeared in the leading 
newspapers, have not led to a more general use of 
evaporators in this country. In Germany it is far 
otherwise, for they are manufactured there in large 
numbers, their use has been constantly extending for 
years, and the director of the " Royal College 
for Fruit and Vine Culture and Horticulture 
in General,” at Geisenheim on the Rhine, not only 
uses them, but has written and published a book in 
which the methods, uses, and benefits of evaporation 
are set forth and strongly recommended. It is not 
improbable that a translation of this book will be 
published in England. It will doubtless be remem¬ 
bered that a report appeared in the London news 
papers in December last, to the effect that the 
Financial Secretary to the War Office had stated 
that dried (/.«. evaporated) vegetables, which could 
only be procured in Germany, and which had been 
recommended by the military authorities, bad been 
purchased for use in the Ashanti campaign. I shall 
be able to show you later on that vegetables have 
been successfully dried in an evaporator in this 
country; and they are dried very extensively in the 
United States. 
From careful notes of the" American ’’evaporator, 
made when 1 saw it at work at the Chiswick Gardens 
in July, 1891, I transcribe the following description : 
—The evaporator consists of (1) a well-constructed 
stove in which there is a surface that consumes any 
kind of fuel, coal, coke, wood, &c., and so creates the 
required degree of heat. This furnace is very 
manageable and only needs ordinary intelligence to 
make full use of its considerable powers. From this 
proceeds (2) an iron pipe through which the smoke 
escapes. This pipe may be lengthened or shortened 
as may be required. Above the stove is (3) a chamber 
in which the cold air is heated to any degree of tem¬ 
perature required. The air being properly heated 
ascends into (4) the trunk (consisting of two flues) 
which rests on the stove at an angle slightly 
inclined. This is the special feature of the 
“American” evaporator on Dr. Ryder’s system, in 
which its undoubted superiority consists. All other 
kinds of evaporators have the evaporating flues 
arranged perpendicular to the stove at their base, 
and the hot air proceeding through them is more or 
less deflected by the fruit placed on the trays, and is 
hindered in its natural progress upwards. Moreover 
the hot air becomes saturated with moisture derived 
from the drying fruit, and consequently becomes less 
efficient for drying purposes. In the " American 
evaporator, the flue being inclined, this serious defect 
is absent. The hot air first plays about the lowest 
trays of fruit in the evaporating flue, and then 
ascends upwards and does a further amount of 
drying as it ascends the flue, on reaching the end 
of which it escapes, carrying with it the extracted 
moisture. 
Apples were the only fruit evaporated on that 
occasion, and as none others were available in July, 
Tasmanian Apples were used. By means of a most 
ingenious and inexpensive little machine the Apples 
were rapidly pared, cored, and divided into slices or 
rings. The prepared Apples were then dipped into a 
bucket containing water, in which a small quantity of 
salt had been dissolved. The rings were next placed 
in single layers on shallow trays, made of wooden 
sides, with bottoms of galvanised wire-cloth of 
somewhat small mesh. A tray (which I will call No. 
1) having been filled with fruit, was placed in the 
ascending evaporating flue of the trunk at its lower 
end, immediately over the hot-air chamber above the 
stove. In about five minutes a second tray was 
filled, and was placed immediately under tray No. 1. 
Then a third try was filled, and placed under No. 2. 
Three trays, one above the other, were all the 
evaporating flue would hold in height. A fourth 
tray being ready to place in the flue, trays Nos. 1, 2, 
and 3 were pushed forward, to admit of its entrance ; 
then trays 5 and 6 were placed underneath No. 4, 
and these were pushed forward, and other trays 
entered, until the entire flue was filled. Trays Nos. 
1, 2, and 3 having reached the end of the flue 
(where thermometers were placed on each side, to 
show the exact temperature), they were carefully 
examined by the operator, to ascertain if any of the 
fruit upon them was sufficiently desiccated. All 
rings in that condition were removed into bags or 
boxes, and as enough were removed from the first 
three trays' to leave one empty, that was withdrawn 
for use again at the lower end, and the second series, 
having been examined, three trays were placed in 
the descending flue, and so on, until the whole of the 
first batch was completely finished. Meanwhile, a 
new supply was placed in the ascending flue at the 
entrance end ; and so the work went on, until all the 
fruit was dryed in a satisfactory manner. The 
entire process lasted about two hours. On October 
5 and 6, 1892, another demonstration took place at 
the Royal Horticultural Society's Gardens, which 
was attended by representatives of the Board of 
Agriculture, the India-office, and some of the 
Colonial Departments, and the results were so satis¬ 
factory, that the society awarded the makers of the 
evaporator their Silver Gilt Knightian Medal. 
It is often supposed that all processes of drying 
fruit yield similar products, but this is a mis¬ 
leading notion. There is, on the contrary, much 
difference in the quality of fruit that is sun-dried or 
kiln-dried and that which is dried in an evaporator. 
Sun drying is still much used in California, but is 
being rapidly superseded by the more scientific 
process. The best explanation I have met with why 
evaporated fruit is superior in quality, is that given 
by an eminent American scientist, Dr. J. F. Symons, 
of Fayetteville, Arkansas, in an address delivered by 
him to an important " Association of Fruit and 
Vegetable Evaporatorsfor the pursuit is of so 
much importance in America that the members of 
the trade band themselves together for the protection 
and advancement of their joint interests. 
Dr. Symons says :— 
“ I will now describe the process of true evapora¬ 
tion. It has been found that by removing a part of 
the water rapidly, in swift-moving currents of air, 
heated from 240° Fahr., a different product is the 
result, wholly unlike the fresh or sun-dried fruit ; and 
which will keep better, is more digestible and nutri¬ 
tious, is less acid, and will sell for more in the 
market. But if, after having heated the air hot 
enough, there is not sufficient circulation, or the 
currents not rapid enough, the fruit will cook and 
then dry, or burn the same as in a close oven. 
Apples will cook in boiling water at a temperature of 
only 212 0 Fahr., or bake in an oven at 225'' Fahr ; 
but if the hdated air circulates fast enough, the fruit 
will not cook or burn or become itself heated to the 
temperature indicated by the thermometer, even at 
300° Fahr., for the evaporation of the water is a 
cooling process, and every particle of vapour 
leaving the minute cells which contained it carries 
with it also a large amount of caloric in a latent 
form, and thus keeps the heat of the Apples far 
below that of the surrounding air. The chemical 
changes which belong to truly evaporated fruit will 
now begin, and the albumen, instead of being slowly 
dried, is coagulated precisely the same as in an egg 
when boiled. The soluble starch existing in all fruit, 
and composed of C B H 10 O s , will, if the heat is high 
enough, combine with one equivalent of water 
(H 2 0 ), so that now we have an entirely different 
compound, to wit, glucose, or fruit sugar, which will 
assist in the preservation of the fruit, instead of being 
liable to decomposition, as dried starch is, in sun. 
dried or slowly dried product. All the pectine or 
fruit jelly remains in the cells undecomposed, or is 
left upon the surface by the evaporation of the water 
in which it was dissolved, and may be seen condensed 
upon the surface, instead of being decomposed, and 
passing on with the starch and gluten into the acetic 
fermentation, The diastase or saccharine ferment 
contained in all fruit, and which is the primary cause 
of its decay, has been rendered inoperative, and all 
germs of animal or vegetable life have been destroyed 
by the high heat. It is by this chemical change 
which I have briefly described, in uniting a part of 
the water already contained in the fruit with the fruit 
starch, that these truly evaporated products are 
rendered more wholesome, more digestible, more 
indestructible, and are thereby made more valuable, 
not only as articles of food, but because they are not 
subject to deterioration and loss. And it is also the 
reason why a bushel of apples will make more pounds 
of evaporated fruit than can be made by sun-drying 
it, as a portion of the contained water which would 
otherwise be lost is retained by combining with the 
starch to form glucose, and the carbonic acid, which 
is always lost in the slow decomposition resulting 
from sun-drying, is retained in its natural com¬ 
bination with the other substances composing the 
fruit, and hence it is heavier. These profitable and 
healthful chemical changes which I have mentioned 
are all in accordance with the laws of nature and are 
certain to take place if the necessary conditions of 
heat and air, as I have detailed them, are properly 
supplied, otherwise you will have a different pro¬ 
duct ; and no matter how fine your Apples, how 
perfect your paring, coring, and trimming, or how 
white you may have bleached them, you have not 
made truly evaporated fruit; and no matter how 
many have been deceived by its bright colour, or full 
weight, or fancy packing, your fruit will not stand 
the test of long keeping in warm, damp weather. 
The natural starch, gluten, and albumen of the fruit, 
instead of being cured or made indestructible by the 
chemical changes which constitute the difference 
between the evaporated and dried fruits, will absorb 
moisture from the air, will swell or increase in bulk, 
and be attacked by mould, will absorb additional 
oxygen, and finally sour and decay.” 
(To be continued ) 
--5*- 
A candid confession —A Carnation hybridist (or 
shall we say cross-breeder?), in making comments 
upon the result of some of his work, said his “ first 
set of seedlings were remarkable for nothing except 
the high opinion he had of them.” 
