414 Miscellaneous. 
collected in one of these trips. Large numbers of them 
are sent to London and Paris, where it is said they are 
preferred to leeches brought from any other place. The 
greater proportion, however, are forwarded to America, 
where the demand is always great. 
ANSWERS TO CORRESPONDENTS. 
T. B.—Cyamelide, the hydrate of cyanuric acid, when kept for some 
time, becomes hard and white, like porcelain ; insoluble in water, 
alcohol and dilute acids subjected to heat, it forms hydrated cyanic 
acid. 
ZETA, Cambridge-—The linen called China-grass-cloth is fabricated 
of the fleshy part of the leaf of the aloe, which abundantly grows 
wild in China. The flax, which constitutes the fishing-lines known 
under the name of Indian twist, is also manufactured from aloe 
fibre. 
PHILOSOPHER.—In the imperfect cubes of boracise, it is conjectured 
that the molecular particles are not in the form of cubes but tetrae- 
hedons, and that very possibly one of these tetraehedons, by pre- 
senting its base at the angle of the general cube of the crystal, 
makes that angle imperfect, while another tetraehedon may at 
another angle present one of its vertices. Similar reasoning is ap- 
applied to the crystals of beryl, quartz, and tourmaline. 
C. H. J., Hdenburgh—lIt has been calculated that, supposing each 
man were to consume a kilogramme of oxygen per day, and that 
the oxygen disengaged by plants did no more than compensate for 
the other causes of its absorption, the whole human race, and three 
times their number, would not consume in a century the eight 
thousandth part of the oxygen which Nature has placed in the 
respirable air. 
K. A——The information you require concerning “ A£rolites,” will be 
found in the number of the TECHNOLOGIST for December, 1866. 
H. SHERWOOD.—Too late for insertion in present number. 
BOOKS RECEIVED. 
Letters from Hell. Bentley. 
Familiar Lectures on Scientific Subjects, by Sir J. Herschel. Strahan. 
Contemporary Review. Strahan. 
The Argosy. Strahan. 
The People’s Magazine. 
Annuaire Philosophique. 
The Artizan. 
Hardwicke’s Science Gossip. 
Victoria Magazine. : 
Goethe’s Minor Poems. By E. Chawner. London: Pitman. 
Systematic Memory. Second Edition. By T. Maclaren. London : 
Pitman. 
Pearce’s Weather Almanac, 1865. Simpkins, 
Pearce’s Weather Guide. Simpkins. 
Pure Dentistry, and What it Does for Us, by A. Eskell. Clements. 
Pharmaceutical Journal. 
Science Gossip. 
