November 9, 1882. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 427 
than any other; but trees against an east wall produce good 
Plums. 
Fan-shape training is the best for walls. Keep the lower 
branches well down and the centre open until the tree is fur¬ 
nished. Young trees do not require the leading growths pruned 
back very much ; only shorten the strongest growths to balance 
the tree, and lay in as many laterals as there is room for, pruning 
1 the others to form fruit spurs. The following will be found a good 
selection either for culinary or dessert in succession Early Pro¬ 
lific, Oullins Golden Gage, McLaughlin’s Gage, Green Gage, Trans¬ 
parent Gage, Jefferson, Victoria, Kirke’s, Belle de Septembre, 
Prince Englebert, Reine Claude de Bavay, Ickworth Imperatrice, 
and Coe’s Golden Drop.—A. Y. 
THE MANURIAL VALUE OF PHOSPHATE OF 
MAGNESIA. 
Roughly analysing the field trials referred to in my two last 
letters (pp. 383 aud 406), we find that from November, 1881, to 
October, 1882, the results recorded in the Journal of the Chemical 
Society stand thus :— 
No. of 
Superphosphate or 
Precipitated or 
Bone dust 
trial. 
soluble acid phosphate. 
retrograde phosphate. 
or coprolites. 
1. . 
2. ., 
S. ., 
4. 
6. . 
6. .. 
7. ., 
8. . 
9. ., 
10. . 
11. . 
12. ., 
13. . 
14. . 
15. . 
.... best 
16. ., 
Thus- 
Dissolved, or perfectly soluble phosphate, gave the best results 5 times out of 16. 
„ „ „ „ „ slightly best 3 „ „ 
„ „ „ « „ equal to preci-1 , 
pit’t’d or reduc’d } 0 ” ” 
doubtful 1 „ „ 
best results 1 „ „ 
slightly best 1 „ „ 
» » „ » « equal with sol-1 , 
uble phosphate j ” ” 
„ „ „ ,, ,, doubtful 1 „ „ 
Bone dust, or powdered coprolite. „ best results 2 „ „ 
So far, then, as the weight of the crops is concerned, we can 
hardly hesitate to place the— 
Perfectly soluble phosphate.... in the front rank of activity and efficiency. 
The precipitated or retrograde.. „ second „ „ „ 
Bone dust or coprolite . „ third „ „ „ 
And these results are in as much accordance as could be expected 
from comparisons made under differing conditions of soil, crop, 
and weather, with the conclusions drawn from laboratory experi¬ 
ments and theoretical reasonings ; but my chief object is to show 
the superiority of phosphate of magnesia and ammoniacal phos¬ 
phate of magnesia to any of these forms of phosphate of lime. 
To this point I now turn from the views of Liebig given at 
page 342 concerning these two magnesian compounds, and from 
the facts stated in my letter concerning the money value of 
magnesia a9 a manure (page 225), it will be seen that theoretical 
conclusions are absolutely in favour of the fertilising effects of 
phosphate of magnesia and its combination with ammonia, and 
the proofs derived from their solubility are most convincing. It 
is, however, a strange fact, that though Liebig’s attention was 
directed to magnesian phosphates he deals only with the tribasic 
form, and does not refer to the bibasic salt, though the solubility 
of the latter is very much greater. Yoelcker, again, when testing 
the solubilities of phosphatic materials, experimented with tribasic 
phosphate of magnesia (his attention being called to it, as was 
Liebig’s, because it is found in the ashes of plants), but he leaves 
the far greater solubility of the bibasic salt unconsidered. This 
could only have arisen, as it appears to me, from the supposed 
impracticability of procuring the latter substance for commercial 
application. Voelcker, in common with Liebig, manifestly be¬ 
lieves that ammoniacal phosphate of magnesia is practically 
sufficiently soluble to meet the wants of all cultivated plants. 
Bousingault, moreover, was much impressed with its manurial 
qualities, and urged its use. Liebig found that its solubility in 
weak solutions of ammoniacal salts was between 8 and 10 grains 
. - - ~ = 
per gallon (page 342). That of bibasic phosphate of magnesia 
far exceeds this. It is, in fact, soluble to the extent of 217 grains 
per gallon at a temperature of 45° Fahr. Now this is a degree of 
solubility which must practically be equal, so far as respects a 
manure, to the solubility of soluble acid phosphate ; and the 
absence of acidity in phosphates is a great desideratum in 
Voelcker’s opinion, as well as in that, I believe, of all agricultural 
chemists, when the manure is applied to land deficient in lime. 
Neither can there be, I think, any difficulty in selling phosphate 
of magnesia, as soluble as the bibasic, with a guaranteed per¬ 
centage, the impracticability of doing which is often advanced as 
an objection to the more general use by farmers of precipitated 
phosphates of lime. 
Of field trials with the phosphate of magnesia I shall refer to 
two cases only—first, to the results obtained with this salt at 
Easter Ardross, the report on which was ably reviewed in the 
Journal of Horticulture (page 110, No. 1766), and secondly 
to a trial which was made by Dr. Hogg at Stillyans in 
Sussex, on Potatoes in the year 1877. This has been already 
referred to by me at page 381 (No. 98). Briefly, Dr. Hogg found 
that “ fimus ” manure, which contains phosphoric acid in the 
form of phosphate of magnesia, produced double the effect he 
obtained with a heavy dressing of farmyard manure ; and Mr. 
Cameron obtained results which showed that 1 lb. of phosphoric 
acid, in the combination to which I have here called attention, 
produced the same effect as 2 lbs. of that substance in soluble 
acid phosphate of lime. Need I add more to encourage horti¬ 
culturists to prove or disprove whether similar effects would 
result from its use in the special soils they may have to deal 
with ? A saving of half the sum now expended on superphos¬ 
phates would be no trifling consideration.— Inquirer. 
SINGLE DAHLIAS. 
Having read with pleasure paragraphs in your valuable Journal 
referring to single Dahlias, I venture to offer as a correspondent 
another contribution from my experiences in the growth of these 
beautiful and popular plants. 
The reputation of Paragon, coccinea, lutea, Vivid, alba, &c., is 
already established, and I have grown them to perfection, but the 
varieties will soon become inexhaustible, as you may imagine 
from my experience. 
A packet of mixed seed was sown in a pan last February. The 
young plants so obtained grew stronger than cuttings. 1 planted 
them in round clumps, and the effect has been very striking and 
brilliant from the variety of colours, the most beautiful I have 
named being a pure crimson Regina ; yellow veiled with red, 
Destiny ; yellow centre, shaded into scarlet and deep crimson, 
Gloriana ; white, shaded into pink, Cecilia ; pure yellow, curious 
shape, Cross Roads. 
The varieties, however, will become endless, and as to the 
nomenclature of single Dahlias it will be impossible to name 
them all. One thing is established—the single Dahlia can be 
grown from seed as an annual. It will commence to bloom in 
July, and as an autumnal-flowering plant there is no better. 
There is a profusion of bloom still, and I expect when the seed is 
harvested to have a still greater variety next year, and hope for 
a successful result in having already associated alba and Paragon, 
as suggested by a correspondent.—P. L. 
SCRAPS ABOUT FRUIT. 
A Double Crop of Plums. —My attention has been drawn 
to a remarkable instance of fruitfulness in Plum trees. We have 
here two trees which have this unfavourable season ripened two 
crops of fruit. The first crop ripened early in September ; the 
second is now ripe. The trees are apparently about twenty years 
old, and I am told in all favourable seasons they bear a second 
crop. The first crop was very like the Victoria ; those ripe now 
are of the same colour and flavour, but differ in shape from that 
variety. Not having seen or heard of such a thing before I would 
like to know if it is usual for Plum trees to bear two crops in one 
season, especially an unfavourable season like the present.— John 
Lindsay, Exton Park, Oakham. 
[Two fruits sent with this communication were crushed into a 
flattened mass of pulp in transit through the post.] 
Large Pears. —I desire to thank your Maidstone correspon¬ 
dent, “ F. O. M.,” for the weight of Pitmaston Duchess Pear 
recorded on page 385. I have grown one of the heaviest, if not 
the heaviest, fruit of that Pear in England ; it weighed 1 lb. 14^ ozs. 
I have one fruit of Beurrd Diel weighing 1 lb. 4^ ozs. I have not 
grown Easter Beurrd before this year; a small tree from the 
ft if it if ff 
Precipitated or reduced (soluble to the] 
extent, say, of 5'56 grs. per gal. oi water) j ” 
if tf fi ft ft 
