November 3,1881. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 395 
should, if there is anything in breed, give an improvement on 
Champion, and lead in the direction recommended by the Potato 
Commission. Doubtless more success would have attended my 
work, but the extreme drought of June caused the berries to drop 
from the sudden ripening at the roots, and later crosses did not 
ripen.—T. Laxton, Bedford. 
PYRUS SALICIFOLIA. 
A note on this deciduous tree may not be out of place now 
that the planting season has arrived. It is surprising it is not 
more planted, and would be perhaps if it was more generally 
known. It grows into a shapely tree when sufficient room is 
allowed it to develope naturally. This Pyrus attains a large size, 
and would be suitable for planting in any position singly. When 
in flower during the month of May a good tree is very beautiful, 
being covered with its snow white flowers. It appears to thrive 
well in smoky positions, and cannot be very particular about soil, 
as it grows here freely in poor soil. When in flower this season 
the bloom was severely injured by frost, but in spite of this it is 
bearing a good crop of fruit. The tree fruits annually without 
fail. The fruits, however, are of no service or beauty, but as a 
flowering tree it is worthy of a place, and is quite distinct in the 
foliage from other trees. The great freedom with which it fruits 
annually has impressed upon my mind that it would in all 
probability prove a good stock for some Pears. I shall be glad 
to know if it has been tried, and if so with what results.— 
Lancastrian. 
PLUMS. 
In the present season we have had a fair supply of Plums, but 
by no means a full crop. Most of our trees, standards, pyramids, 
bushes, and espaliers, flowered well ; but frost and keen winds 
left many of the trees without fruit. In other respects it has 
been an advantage. The trees have made clean healthy wood 
and promise well for another season. Mildew and aphides have 
not been so numerous as in some seasons. We commenced 
gathering at the end of July from trees on the wall having a 
60 uth aspect, from Rivers’ Early Favourite and Rivers’ Prolific, 
two fine Plums for all purposes when well ripened ; soil light loam, 
gravelly subsoil. Prdcoce de Tours is useful for all purposes ; south 
wall and aspect, strong loam, clay subsoil. Early Violet, a very 
desirable early Plum, ripens about the middle of August. I have 
a doubt about the accuracy of the name: can this be the Royal 
Hative of the “ Fruit Manual 1 ” Orleans comes next; and on a 
wall with a south aspect the fruits are abundant and fine. I 
cannot dispense with it. Victoria, very fine, one of the most 
useful Plums we have, especially for market. Kirke’s, a splendid 
Plum on south and west walls, has not been so plentiful as we 
could wish, but remarkably fine and of the best quality. The 
indispensable Green Gage has done us good service ; the quality 
needs no praise. Its purple compeer must accompany it. No 
Plum in cultivation can surpass this for quality. They are free 
growers, answer well in many places as standards, and are good 
bearers. Bryanston Green Gage is a fine Plum, but lacks the 
quality of the above when partly shrivelled ; it is very good. 
Washington has been remarkably fine ; it is an excellent variety, 
one of the very best, and ought to be more frequently met with. 
Jefferson’s has had a moderate crop, but of good quality from a 
west aspect. White Magnum Bonum was not so plentiful as we 
could wish, but the quality has been all that could be desired. 
Golden Esperen is rather scarce but good ; it does well with 
us in a west aspect. La Delicieuse is a fine late variety, with 
fruits of large size and good quality ; it succeeds as a standard, 
and the fruit hangs well on the trees during September and 
October. Reine Claude de Bavay, one of the very best late 
Plums, abundant and fine, of first-rate quality, south and west 
aspects, hanging to the end of October. Coe’s Golden Drop had 
a moderate crop and fine ; it needs no praise, south and east 
aspects are the best, the fruit hanging till November. Many 
others 1 might enumerate, but those given have ripened in the 
order named, and have done us good service for all purposes.— 
P. D., Yorkshire. 
The Late Gale in St. James’s Park.— Although well acquainted 
with the Park for moi'e than thirty years, I do not remember having 
noticed so much damage done by one day’s gale as in that of October 
14th. The line of old Elms on the north side of the enclosure were 
the special sufferers thereby. In several of the fallen trunks I ex¬ 
amined the larvae of the goat moth had evidently been at work, but 
I did not, on a cursory inspection, discover any traces of the beetle 
(Scolytus destructor), which was formerly so harmful to the Elms of 
this and the adjacent parks. Two trees had been torn up by the 
roots that were to all appearance sound. This may be attributable 
to the effects of the drought of last summer, and to the succeeding 
influence of the heavy autumn rains.—J. R. S. C. 
BOILERS versus WATER. 
I READ with much interest Mr. Ollerhead’s account of his 
boilers on page 281, and must say he deserves commendation for 
his perseverance and the success of his work. It was a bold act; 
few would have attempted it, and I am afraid there are not 
many will begin such a job notwithstanding his example. As Mr. 
Ollerhead asks for the “ experience of others on the furring of 
boilers, and the means of preventing it,” I give my opinion on 
the subject. It seems strange that the subject has not been 
noticed before this, at least I do not remember seeing it dis¬ 
cussed ; and as others in the neighbourhood who use the same kind 
of water must have their boilers in a very bad state, their coal 
bills and labour must have been great to keep up the required 
heat in the past cold winters. 
Incrustation is generally caused by the deposition of calcareous 
matters on the heated surfaces of the boiler. Most water except 
rain water contains lime or magnesia (or both), held in solution 
by carbonic or sulphuric acid, and such water is generally called 
“ hard.” The effect of this hardness is familiar to most people. 
It destroys soap in washing, and when water of this nature is 
boiled in a kettle there is a deposit or cake formed over the inner 
surface. This deposition or solid hard layer of matter is caused 
by the decomposition of the bicarbonate of lime or magnesia 
present in the water when heated. Carbonates of lime and mag¬ 
nesia are insoluble in water, but when there is excess of carbonic 
acid, invariably the result of decomposed organic matter, the 
carbonates combine with this excess and become bicarbonate. 
These are soluble in cold water. 
On heating such water this excess of carbonic acid is elimi¬ 
nated, and ordinary carbonate of lime and magnesia are deposited. 
These as a rule form the scale on boilers. Sometimes, however, 
the water holds sulphate of lime in solution, and this substance is 
deposited on the inner surface of the boiler and tubes by the 
gradual evaporation of the water. This form of deposit is more 
difficult to deal with than the carbonates, as it adheres more 
closely, and is much harder and tougher than the deposits caused 
by carbonates. 
In steam boilers for both land and marine engines this deposit 
is the cause of great annoyance, loss of heat, and danger to the 
boilers, as well as a fruitful source of accident, causing destruc¬ 
tion to life and property. Many nostrums have been sent out to 
steam users, all of which in some way had a claim to respect : 
Potatoes, sawdust, seaweed, zinc plates, and chemicals have been 
tried and used in certain cases, but a general cure has been diffi¬ 
cult to provide until the subject was looked at really in a chemical 
manner. 
When water containing bicarbonate is heated the excess of 
carbonic acid, as has been explained, is expelled, and a deposit of 
chalk in a hard form adheres to the boiler. So also in water con¬ 
taining sulphate of lime, there is a deposit formed which soon 
accumulates and forms a solid layer between the heated walls of 
the boiler and the water inside. This is a non-conductor of heat, 
and the result soon follows— i.e., that the iron burned or blistered, 
requiring a great amount of expenditure of fuel to heat through 
the deposit and reach the water beyond, the water is practically 
enclosed in a jacket of iron (the boiler), inside which is another 
jacket of incrustation, which everyone knows is a very bad con¬ 
ductor of heat. 
The simplest and best cure for this is to introduce periodically 
a quantity of ordinary washing soda, the proportion varying 
with the size and work required from the boiler. From 2 to 
7 tbs. will amply suffice for any ordinary boiler, say with 200 to 
800 feet of 4-inch pipes : this, introduced once a month, will 
entirely prevent incrustation. With the number of feet of piping 
to Mr. Ollerhead’s boiler 28 or even 56 lbs. would need to be intro¬ 
duced into the supply cistern of his boiler. The action of the 
washing soda is peculiar, as it, in place of allowing the deposit to 
form into a cake, causes the carbonate to fall in the form of a 
mud, whilst it decomposes the sulphate of lime. This mud must 
be removed periodically, which is simply done by flushing the 
boiler and opening the relief cocks. Old dirty boilers must be 
cleaned as Mr. Ollerhead did his ; for while the washing soda, 
or still better caustic soda, American ash &c., prevent incrusta¬ 
tion, it will not dissolve or remove incrustation already formed. 
Knowing the bad effects hard water had on boilers I always used 
soft water, and we had never any deposit in ours. After being 
nine or ten years in, there w : as only a small quantity of mud, 
but nothing to injure the boiler. In the case, however, of the 
boiler behind the kitchen fire in the mansion, where it was boiling 
