THE TROPICAL AGRICULTURIST. [September i, 1887. 
PELSPAR AS A POTASH MANUBE. 
Sir, — I observe in your issue of the 20th instant 
that Dr. Aitken has made some successful experiments 
on the manurial properties of ground felspar. Ordinary 
pink felspar, known mineralogically as orthocla.se, 
forms one of the constituents of granite and consists 
chiefly of sillica alumina, and about 12 per cent, of 
potash. As felspar is generally regarded as an insoluble 
mineral, it may be of interest to draw attention to 
a series of experiments on the solubility of various 
minerals, described by Mr. A. Johnstone in the lately 
published Transactions of the Edinburgh Geological 
Society. At page 282, vol. 5, Mr. Johnstone states 
that he took three pieces of orthoclase, and after 
carefully weighing them put them into separate vessels 
containing distilled water saturated with carbonic acid 
gas, and allowed them to remain immersed for three 
months. 
The first specimen was placed in a flask, which 
was thsn corked and put away on a shelf, where it 
remaiued motionless during that period. The second 
was suspended in a beaker, the water in which it 
was immer.-ed being agitated for about ten minutes 
every day for the three months. The third was 
placed in a shallow rii-h and barely covered with 
the carbonic acidulated water so that the upper surface 
of the crystal was nearly in close contact with the 
air. The water was gently shaken for about ten 
minutes every day duriug the three months. 
Wben the specimens were examined at the end of 
that period, the first had become slightly softer on 
the surface than before, but had scarcely deoreased 
in weight and the liquid surrounding it, when evaporated 
down scarcely left any residue. The second specimen 
was decidedly softer, and the solution left a residue 
containing potash and carbonic acid, with traces of 
lime and soda. The upper surface of the specimen 
which had been in almost close contact with the 
air was found to have altered its appearance and to 
have changed its bright translucent aspect and become 
covered with an opaque dust-like crust of kaolin. 
Th« solution left a larger residue consisting of potash, 
soda and carbonic acid, with traces of lime and silica. 
In these and other experiments on various felfpathic 
minerals, it was always found that decomposition takes 
place fastest when the water is in ready contact with 
air. The more air, in fact along with water, the 
more rapidly desintegration proceeds. These results 
are agriculturally of interest as they show the com- 
parative ease and rapidity with which felspar can 
be decomposed and its alkaline ingredients dissolved 
out. The experiments were made on single crystals 
of felspar, with the smallest possible surface on which 
the atmospheric disintegrating elements could work. 
By grinding the mineral, and so enormously increasing 
the surface, the alkalies might be practically all ex- 
tracted in a season, if the powder were used as a 
light manure. 
The felspar used in Dr. Aitken's experiments was 
obtained from Norway ; but there is no need of going 
so far a field as this mineral exists in abundance in 
the remote parts of our own Highlands, and in some 
of the very poorest districts where the crofters are 
most in need of employment. The western coasts 
of Sutherland and Ross, with the whole of the outer 
Hebrides, consist of barren tracts of gneiss, traversed 
by multitudes of veins of pegmatite, — a coarse variety 
of granite, chiefly made up of orthoclase felspar. 
Water power is often abundant in these poverty- 
stricken parts of Britain, and the mineral might there 
be quarried and ground, and shipped to the south 
at a cheap rate. — H. M. Oadell, in North British 
Agriculturist. 
THE ROYAL BOTANIC GARDEN, 
CALCUTTA. 
AnitaU of the Uoyal /Satanic Garofiyi, Calcutta. Vol. 1. 
The Species of Ficus of the Indo-Malayan and Chinese 
Countries; Part 1. I'akeomorphc and Urosfcigma. By 
George King, M. B., v. E. s., &c, Superintendent 
of the Royal Botanic Garden, Calcutta. (London; 
Reove and Co., 1887.) 
Dr. King deserves well of botanists for his protract- 
ed, though evidently profitable, labours on so varied 
and difficult a genus as Ficus. Prom obvious causes 
a large proportion of the large arboreous tropical 
genera of plants are still very imperfectly known, and, 
prominent among them, Ficus; therefore Dr. King 
could hardly have extended his researches in a more 
useful direction. The present publication, which, from 
its general title, we may assume wdl not be limited, 
to a monograph of the Asiatic species of Ficus ; is a 
tall quarto of sufficient size to illustrate adequately 
almost all the species of the genus in question. Indeed, 
this monograph possesses a quite special value, inas- 
much as every species is carefully figured in natural 
size, with enlarged analyses of the floral structure. 
Most persons interested in such matters will be 
familiar with Fritz Miiller aud Solms Laubacb's invest- 
igations of the sexual conditions in the flowers of 
various species of Ficus, and the singular phenomena 
attendant on the fertilization of the ovules. Neverthe- 
less, it may be convenient to give here a brief account 
of the process.* The edible fig, which may be given 
as an example of the fruit of the genus generally, 
consists of a thick hollow receptacle, the inner surface 
of which is thickly studded with flowers; and, in the 
edible fig, exclusively with female flowers. Male 
flowers of this species of fig are borne on different 
plants, called the caprifig ; and associated with these 
male flowers, in the same receptacles are numerous 
female flowers, occupying the greater part of the space. 
Invariably these female flowers are infested by gall- 
producing insects, hence they are termed gall-flowers, 
and very rarely indeed is a single ripe seed found in 
a receptacle of the caprifig. The ius^cts hatched and 
nourished in the gall-flowers leave the receptacles of 
the caprifig at a period when the pollen of the male 
flowers is being shed, and in making their exit bear 
some of it with them to the receptacles of the edible 
fig, which they next visit ; but they are unable to 
deposit their eggs in the perfect females, and only 
serve to convey pollen to them. On similar mutual 
adaptations the fertilization of all the species of Ficus 
seems to depend. 
In an introduction to the descriptive part of his 
work, Dr. KiDg details the results of his own examin- 
ation of several hundred sp?cies, extending over some 
nine years : and he states that Solms-Laubach anticipated 
him only in his explanation of the -true nature of 
the "gall-flowers," for he had found them in every 
species of the genus that had come under his notice. 
He also enters into some further particulars concerning 
the insects actiug in the process of fertilization, though 
he adds nothing more conclusive. "While admitting, 
and even assuming, that the pollen of the males must 
be conveyed by the insects developed in the gall- 
flowers " to the perfect female imprisoned in the 
neighbouring recepacles," he is still puzzled as to the 
way in which it is done. Wc are uuder the impres- 
sion that Solms-Laubach indicates, if he does not 
actually state in so many words, that he had not 
frequently seen the winged female insect issuing from 
the receptacles of the caprifig, but that he had 
likewise occasionally observed them enter the repec- 
tacles of the cultivated fig, which is the female 
of the same species. 
This, the first part of King's monograph, con- 
tains descriptions aud figures of seventy-six species of 
Ficus, whereof ten belong to his sectiou Pahcomorphe, 
and the rest to Urostignni, which was originally pro- 
posed as an independent genus by Gasparriui, aud 
provisionally retained as such by Miquel. King found 
five different kinds of flower, variously associated or 
removed, in the Asiatic species of fig; and upon char- 
acters derived from the differentiation and arrangement 
of the sexual organs he classifies the species in two 
primary groups and seven sectious. The species of 
the relatively small group PaltiomoTjSKe are distinguish- 
able from all the others by having spuriously bisexual 
flowers associated with gall-flowers, while the fertile 
females occupy separate receptacles. In the defin_ 
itions of tin; sections, the pistil in the functionally mal e 
* Further details will be fouud in Nature, vol. xxvii 
p. 584. 
