Notes. 
7°9 
i 8 7 9 -] 
methods of conveying acids, we learn that M. Kuhlmann, in 
place of carboys, employs floating reservoirs in the form of an 
ordinary boat, fitted with air-chambers to give them sufficient 
buoyancy. For sulphuric acid of 6o° B. and upwards these are 
constructed of sheet-iron, and have been in successful use for 
some years on the canals of the North. For hydrochloric acid 
he uses cylinders of hardened india-rubber, kept in their form by 
an external framework of wood. A modification of the structure 
serves for transport by rail. 
The value of aluminium sulphate as a disinfecting agent is 
ascribed by A. Tedesco in “ Die Chemische Industrie ” to the 
following action : — The ammoniacal products of decomposition 
are fixed as ammonium sulphate ; the liberated aluminium 
hydrate carries down all suspended particles, forming with them 
a solid precipitate. The organic cell, in contact with aluminous 
compounds, absorbs alumina with great avidity, losing thereby 
its vegetative power, and putting an end to the process of 
decomposition. Herr Tedesco considers bauxite and wochenite 
the best materials for the preparation of a sanitary sulphate of 
alumina. Kaolins are readily attacked by sulphuric acid, but are 
poor in alumina and comparatively costly. 
The influence of the chemical composition of water in the 
preparation of raw silk is pointed out in a communication from 
the Instituto Technico Superiore of Milan. In silk are distin- 
guished the soluble constituents, “ varnish,” or “ gum ” and 
colouring matters, and, on the other hand, the insoluble fibre. 
The soluble constituents give raw silk its brightness, colour, and 
strength, and should therefore be preserved as far as possible. 
For the purpose of unwinding the cocoons the natural gum 
should be softened, but not dissolved. According to Franceson, 
silk, if deprived of all its soluble constituents, loses at the same 
time its strength and elasticity. The authors of this paper find 
that though the loss of strength is proportional to the loss of 
soluble matter, the elasticity is but slightly diminished. In 
order to minimise the loss sustained in softening the cocoons 
hard waters are used, and soft waters are artificially modified by 
the addition of sulphate of lime and carbonate of soda. Silks 
which are to be dyed bright colours, however, should be spun 
out of soft water. 
An improved device for testing petroleum oils, brought out by 
Mr. Holly, is described by “ The Engineering and Mining 
Journal.” With the common oil-tester it is extremely difficult, 
even for one skilled by long practice, to get reliable results 
except by taking the mean of a number of tests, since the 
approach of a jet of flame, however small, to the surface of the 
oil, as usually practised, destroys the accuracy of the test more 
or less, either by the local heating of the oil or by the production 
of disturbing air-currents. Mr. Holly modifies the apparatus 
usually employed by arranging the poles of a battery within 
