382 
THE TROPICAL AGRICULTURIST. 
[December i, 1891. 
vntion of Iho shell for which fnoilitics well be provided 
in the Bill drafted for Parliament, 
This will, we nnderstaud, bo Mr. Saville-Kcnt’s Imt 
official visit to Thursday Island in ronneotion with 
his present eugsEetnont by the Queensland Govern- 
ment, Mr. Kent has received an invitation from the 
West Anslralian Goveremont to report and advise upon 
the pearl shell and other fisheries of that colony 
on the termination of his engagement hero. He has 
however decided to return to England first for at 
least a jcar or two, for the purpose of supervising 
the publication of one or more comprehensivo works 
on the fish and fisheries of Queensland.— J'on es Straits 
Pilot, Ang 2'Jtli. 
[The above refors, of course, to the largo mother- 
of-pearl abells, but has a close bearing on the 
treatment of our small pearl oysters, for culture 
and pearl formation.- En. 7'. -I.J 
ECHOES OF SCIENCE, 
Captive ballcons soi m to be p cnliarly lirb'e to bo 
struck by lightning. M'ithin the last si.v or seven 
years no {'■wertban three have been destroyed in tliis 
way, and the total number of them cannot bo great. 
Theie was one struck at Turin, another at Barcelona, 
and, lastly,^ one at Chicago. Two of these, including 
that of Chicago, wore struck when moored near the 
ground. Of course, a captive talloon in connection 
with the earth rcaemblos the kito of Frankliu, and 
is liable to “ draw ” the discharge, but the fact that 
it contains hydrogen, which is a far better conductor 
of eleotrioty than air, may have something to do 
with tho matter. The siik bag with hydrogen may 
be compared to a mass of metal enclosed in a 
thin layer of ii sulator. 'When, as hnppens in ill- 
made balloon.s, the gas escapes through the pores, 
the lightning is tempted in that direction. Cliffard’s 
imi>ermeable balloons have not as 3 et boon struck. 
It may be added that anrouauts, remembering tlie 
conductivity of hydrogen, should avoid opening tbe 
valves of their balloons while paming below a thunder 
cloud, in case they shonld precipitate the discharge 
It is Well known that the valley of tho Orinoco 
is connected to that of tho Rio N’egro by the 
Cassiqniares river, and it is here that a parly 
of explorers have recently discovered immense 
forests ef the india-rubber trees, as well as other 
trees very like, if not indentical, with the gutiapereha 
trees of the Malay Arohipolago. As tho latter 
are all hut extinct now, tlio news is all tho more 
important. — Glohe. 
NOTES OF POPULAR SCIENCE. 
By Du. J. E. TAvr.OR, I'.d.s., &c., 
EniTon OF “ Science Gossip.” 
Two French mineralogists, Messrs. Fouqnd and 
Ldvy, have produced micaoi oiis trachyte hy artificial 
moans. Tho trachite was obtained by the attificinl 
action of water underpressure on a glass rosiilling 
from granite, and at a bright-r,d heat. Tho rock 
was homogeneous, and in its sections exhibited beauti- 
ful ootohedral crystals of a variety of spiral, in 
connection with orthoclase and black mica. 
An important paper was read before tho (jee'ogical 
Society recently by Mr. ,1. Lister, on the geology 
of tho Tonga Islands. Many are purely volcanic iii 
structure, bnt there are forao pussessing undoubted 
stratified limestones crowded with marine shells, 
showing evidences of elevation from oonsIdi-raMe 
depths of tho sea. Mr. Lister also discovered genuine 
Plutonio rooks on the islands. Tho paper has an 
important bearing on the origin of coral reofs. 
There is pirhaps, not a mors useful natural order 
of plants in the world than theorucifertn— our inus'ard.s, 
ori 880 ', turnips, radishes, &c. All are remarkable for 
their pungency, and equally so for the localisation 
of this quality. Bometimes it is situated in one part 
sometimes in another. Moreover, it has long been 
recognised as largely due to sulphur, and auyhody 
who h .18 had to do with the waste products of 
cruciferous p'ants, from cabbage water toretieii turnips, 
is well atvaro they freely give off a largo quantity of 
sulplinrottod hviirogeii gas. A Fionch agricultural 
chemist has just shown that tho composition of the 
various active principles of the ernoiferin varies from 
species to species. Blsck mustard contiiins linigrin, 
be*idoa the ferment myrosin. Tbe horse-ra lisli does 
the tamo. White mustard contains siiialbin in place 
of siiiigrin. The active principle of wnterore.ss is 
sulphocvaiute of bntyric alcohol. The roots, stems, 
leaves, Ac., of otlier common ernciferous plants contain 
a mixture of sulphur and sulphocyanato of allyl. M. 
Guigiiard concludes that nearly all cruciferous plants 
are provided with special cells which contain a 
particular ferment known as myro-iin; and that it 
IB in the colls of tbeir seeds this occurs most abun- 
dautly. 
The methods by which plants obtsiu their nitrogen 
are always fruitfnl subjects ef discussion and interi’st 
to botanists. Two CL rinau natural sis have recently 
published the rouilts ot tome prouBar experiments, 
chiefly cn the leaves of legnmiiioiia plants. They find 
that green leaves ooiitnlii more uitrogeu in the even- 
ing than on the following riioriiiug, and this appears 
to depend on the qoanlity of asparsgin being larger. 
The resfon given is that nspanngin and sugar are 
the best nutriaiits for tlie fungus which livoa sym. 
biotioally ou tho roots of most leguminous plants. 
The largest proportion of nitrogen pressat in tho 
evening was iu three coiiimon leguniiuous plants — 
T ifoliuni prateme (or o.immon clover), Medicago 
saliva (common mediok), and l.athyrus sylvestris. 
Tlio saiiio fact was noticed in coniiection with herbage 
plants belonging to otUir tia'ural or.iers. The moral 
of I his discovery lecms to bo that we ought to out 
our hay at night, and not begin in the morning an 
is usually the case, if wc wi.-li it to ounlain the 
g.-eatest quiuitity of nitrogen or f.-eding stuff. 
Mr._ Cariis.AV'ilaoii 1-as for tome years past been 
studying tho phouoiiiena of ** riiusica’ sand,” or sand 
grains whose movements give out musical soumis. He 
writisiu the t'heoiical Stws Xo say he has sucecedod 
in producing musical notes from sand which was 
never before mu.'ioa', and that lie has obtained 
similar results from the mute or " killed ’’ musical 
sands which have tieen temporarily deprived of their 
musical properties. Frofiesor Crookes adds a note 
to Mr. Wilsun’s oommunioatiou, stadng ho Iiad wit- 
mased tliat geulleninn's experinients with musical 
sands, tands originally mu»io»l, miiMcal fiiiida which 
liad been killed sud then revived, and sands ori- 
ginally mute which had- had the gift of music con- 
ferred upon them. Mr. AVilsoii will shortly explain 
these interest iiig phenomena in detail. — Austral'isian. 
THE GREATEST BUTTER COW OF 
THE WOULD. 
In our last September issue we gave an illustration 
of tho celelirated Jersey cow “ Eurolisama, ” do-cri- 
bing her as the greatest biittrr cow of the world, slio 
having produoj d the up till tliat time, iiiilie.ird of 
amount ot ‘J-lo pounds, U , u, ocs of good merchantable 
bnttor witliiu tho yiar. Wo little thought, then, that 
within six nioiiths we shoui i have to depose her from 
the ]) imaclo of fame, an-i lank lior only second in tlie 
list, and yet eucii is onr position io-dav. Tlio Ilolsteiii- 
Friesiancow " Pauline Pan', ” owned hy J. B. Dntcher 
A Son, ol _PauIing, New York, has just completed a 
butter production, and has iniido 
within tliat tune tlie iiiiparallelcd rorord of 1J5S povnds, 
15^ ounces ot maiketable hiiiter. Will wa.shed, and 
salted ot the rate of one ounce to the pound. We 
have not the details of the food consumed, beyond the 
Tact that she was fed a ration composed of three parts 
bran, two parts ground oats, and one part corn inea', 
by lu^surc. Of this mixture, she was fed per day not 
oxcocdiug twenty-seven pounds, to whioU was added 
three pounds ot cotton seed. Slie had neither slop nor 
