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PHIPPS’S JOURNAL;
LS.)
Lichen cornutus. Linn. Spec. Plant. 1620. 64.
Lichen rangiferinus. Linn. Spec. Plant. 1620. 66. -
Lichen globiferus. Linn. Mant. 133.
Lichen pafchalis. Linn. Spec. Plant. 1621. 69.
Lichen chalybeiformis. Linn. Spec. Plant. 1623. 77.
Account of Doctor Irving’s Method of obtaining frefh Water from the Sea by Diftillation.
As the method of rendering falt water frefh by diftillation, introduced by Doétor
Irving into tae Royal Navy in the year 1770, and practifed in this voyage, is an ob-
e&t of the higheft importance to all navigators, and has not hitherto been generally
noir I have added the following very full account of its principles, apparatus, and
advantages, with which I was favoured by Doétor Irving himfelf.
** Previous to an account of this method of rendering fea water frefh by diftillation,
it may not be improper to give a fhort detail of the experiments which have been for-
merly made by others on this fubject ; pointing out at the fame time the feveral difad-
vantages attending their proceffes, and the general caufes which obftruéted the defired
fuccels. 5
“< Without entering into an account of the earlier experiments, it will be fufficient to
take a view of fuch as have been profecuted with moft attention, for the lalt forty years.
“« The firft of thefe was the procefs of Mr. Appleby, publifhed by order of the Lords
of the Admiralty, in the Gazette of June 22d, 1734. By the account of that procefs
it appears, that Mr. Appleby mixed with the fea water to be diftilled, a confiderable
quantity. of the /apis infernalis and calcined bones. The highly unpalatable tafte of the
water, however, exclulive of the extreme difficulty, if not impoffibility, of reducing the
procefs into practice, prevented the further profecution of this method.
*¢ Another procefs for procuring frefh water at fea, was afterwards publifhed by
Doétor Butler. Inftead of the /apis infernalis and calcined bones, he propofed the
ufe of foap leys; but though the ingredients were fomewhat varied, the water was
liable to the fame objections as in the preceding experiment. Dottor Stephen Hales
_ ufed powdered chalk ; and introduced ventilation, by blowing fhowers of air up through
the diftilling water, by means of a double pair of bellows. It was found by this method
that the quantity of frefh water obtained in a given time, was fomewhat greater than
what had been procured by the procefs of Mr. Appleby. This invention, however, was
fubjeé to feveral difadvantages. The air box which lay on the bottom of the {till, as well
as the chalk, much obftructed the ation of the fire upon the water, at the fame time
that the boiling heat of the latter was diminifhed by the ventilation : fo that more
than double the ufual quantity of fuel was neceflary to produce the fame effeét. Bee
fides this method by no means improved the tafte of the water.
“ The next who attempted any improvement was the learned Doétor Lind, of
Portfmouth. He diftilled fea water without the addition of any ingredients; but as
the experiment he made was performed in a veflel containing only two quarts, with a
glafs receiver, in his ftudy, nothing conclufive can be drawn from it for the ufe of fhip-
ping. Indeed experiments of the like kind had been made by the chemifts in their
laboratories, for at leaft a century before.
“¢ In the year 1765, Mr. Hoffman introduced a ftill of a new conftrudtion, with a
fecret ingredient ; but the large fpace which this machine occupied, being feven feet
five inches, by five feet eight inches, and, with its apparatus, fix feet {even iaches high,
‘made it extremely inconvenient: at the fame time that, on account of its fhallow form,
. VOL, Is 4F the
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