New Scientific Processes and Inventions. [March, 
hitherto been employed. The commercial sulphate of alumina 
so called cake-alum — is dissolved, precipitated with an alkaline 
carbonate, and the precipitate re-dissolved in hydrochloric acid. 
Hence its price has naturally been greater than that of the sul- 
phate, and the latter salt has therefore been employed in prefer- 
ence. There is, however, one class of purposes for which the 
chloride of aluminium would at equal prices be preferred to the 
sulphate. Several years back it was very justly remarked by 
Mr. Crookes that the settlement of the sewage question must to 
a great extent turn upon cheap soluble alumina. The power of 
alumina in such states to seize upon organic matter not merely 
when suspended, but when dissolved in water, and to precipitate 
it in combinations of which “ lake-colours ” are the most familiar 
type, is well known to practical men. How many of the every- 
day operations of the dyer and the colour-maker entirely or 
mainly depend upon this very power I need not stay to point out. 
That the action of aluminous salts upon fcecal matter is closely 
analogous to their behaviour with tinctorial principles must be 
admitted when we see that, according to the recent official inves- 
tigations of Dr. R. Angus Smith, the “ albuminoid ammonia,” 
or organic nitrogen, in the effluent waters from the Aylesbury 
Sewage-works, was found as low as 0*024 grain per gallon, — a 
little more than one-fifth of the limit proposed as admissible by 
the late Royal Rivers Pollution Commission. 
Yet so long as the soluble salts of alumina were high in price 
results such as the above, however interesting from a theoretical 
point of view, were of little value to the practical sanitarian. 
Soluble alumina, in the form of sulphate, has indeed experienced 
a remarkable reduftion in price during the last eight years ; but, 
thanks to M. Fournier, its future cost in the state of chloride 
will be even lower than it is at present. Nor. should it be. over- 
looked that, other things being equal, chlorides are decidedly 
preferable to sulphates for sanitary purposes. 
The aluminium chloride prepared as described above is not 
applicable to dyeing and to the destruction of vegetable matter 
mingled with wool, on account of its contamination with iron, 
an impurity which in the treatment of sewage and night-soil is 
by no means objectionable. But for the preparation of a pure 
aluminium chloride M. Fournier proposes to use the ordinary 
cake-alum as a starting-point. This salt is dissolved, mixed 
with a proper proportion of brine, and refrigerated as described 
above. The results are Glauber’s salts and aluminium chloride 
fit for the so-called “carbonisation ” of wool, and of course cheaper 
than that obtained in the ordinary manner. 
Another French inventor, M. Pechiney, of Salindre, in order 
to utilise the “ sel mixte ” of the salt-works on the Mediterranean 
coast, a mixture of common salt and of magnesium sulphate, 
exposes the lyes by means of Carre’s ice-machine, to a temper- 
ature of - 6° C. The results are analogous to those obtained in 
