S90 F I 
that gentleman’s trials, and the large fcale on which they 
were made, left no doubt of his fuccefs. Finding, how¬ 
ever, that the particulars of the preparation were with- 
holden from the public, M. Nydroem conceived that it 
might be wonli while to communicate his own refults, 
which are as follow : To ioo parts Swedifli kanns, equal 
to three quarts Englilh, of water, he fepararely added 
one or other of the fubjoined materials or mixtures : 
12 parts of the flrongeft ley, io of decrepitated and dried 
culinary fait, 15 of the flrongeft herring pickle, S of le¬ 
vigated pot aflves, 10 of dried and levigated green vitriol, 
1 2 of levigated alum, 20 of dry levigated clay, 10 of a 
mixture or equal parts of clay, green vitriol, and common 
fait, 1 2 of equal parts of ftrong ley and clay, 10 of equal 
parts of colcothar, from the diftillation of aqua fortis and 
common fait, 10 of equal parts of colcothar and herrring 
pickle. 
Thefe proportions were found by fpouting water from 
a fyringe on embers and on rolin mixed with tow, faw- 
dult, oil of turpentine, &c. in full blaze. Combuftible 
materials were alfo rendered incombuftible by intmerfion 
in faturated folutions of fome of the above enumerated 
materials in boiling water. Red-hot charcoal, being kept 
immerfed in them for a few minutes, and afterwards dried, 
did not take fire in confequence of melting a bit of bif- 
muth on it by the flame of a blow-pipe ; and inftantly as 
the dream of air ceafed to be direfted on it, the ignited 
point difappeared'. Padeboard dipped in th.efe folutions, 
and dried, did not burn in the flame of a candle. Rofin, 
fufed with an equal quantity of the incombudible mate¬ 
rials, took fire with difficulty in the flame of a candle, 
and foon went out. 
Water alone, fays M. Nydroem, is a perfectly good 
material for extinguifbing fire : but, as it is driven up in 
the form of fleam by the hear, the addition of other fixed 
incombudible materials becomes nccelfary ; for thefe pe¬ 
netrate the pores of burning fubdances, and, by prevent¬ 
ing the accefs of air, not only extinguifh them, but hinder 
the fire from breaking out again. If any one choofes, 
he may take as much extinguifhing material as water ; 
and this will be liquid enough to be injefted. In order 
to prevent the powders from getting into lumps when 
much water is added to them at once, they fliould be fird 
made into a pade with water in feparate veflels. 
In anfvver to an objection deduced from the expence of 
preparing and keeping the extinguidiing preparations, 
M. Nydroem makes the following remarks : 1. All falts 
may be kept from crydallizing by a lufficient quantity of 
water in clofe veflels ; but, as unufually fevere cold may 
occafion the bunding of the veflels, and, as liquids re¬ 
quire more fpace titan powders, alkaline ley and brine 
are the only fubdances fit to be kept in this manner. 
The tendency of fome powders to attraft moidure, and 
to run into lumps, is not a great inconvenience. Many 
mineral falts, when dried and pounded, attraft no 
moidure, viz. alum, vitriol of zinc, of copper, and of 
iron. The lad, which is the cheaped, after having been 
dried by a gentle heat fo as to be capable of being 
pounded, does not deliquefee. Colcothar, from the aqua 
fortis rnanufaftory, which con (Ids of vitriolated tartar and 
calcined iron, is as efficacious as vitriol of iron, or any 
other mineral fait, mixed with earth : it is eafily pounded, 
and it is not deliquefeent. The tendency of common 
fait to deliquefee is obviated by dry clay ; which addition 
has two advantages, as it prevents the caking together of 
the falts, and, by covering the furface of the burning 
materials, prevents the accefs of air. Clay and alkaline 
ley form one of the cheaped materials. Lime, where it 
does not deliquefee with the fait employed as it does with 
common (alt, is as good as clay : but the latter prevents 
the engine from being hurt by the falts; though, when¬ 
ever it is tifed, it ought to be well rinfed with clean water. 
In cities or towns, a mixture of clay, vitriol, and fait, 
or of fait and colcothar from the aqua-fortis works, will 
perhaps be mod eadly procured ; in the country, clay is 
R E. 
recommended with alkaline ley, or brine. Of the fimple 
materials, whichever is at hand may be taken. The ley 
or brine mud not be mixed with the clay before it is ufed. 
The difference in point of efficacy is not material. Much 
depends on the preparation, and on the proportion to the 
water. In a fublequent paper, M. Nydroem fays: “I 
find a thick mixture not at all prejudicial to the quicknefs 
or height of the fpouted dream ; and the more extin¬ 
guifhing material is taken in proportion to the water, the 
fooner is extinction edefted. The bed way is to ufe a 
thick mixture till the violence of the fire be over ; then 
a thinner mixture or water alone will fuffice. The fol¬ 
lowing proportions make a thin pade, and may be diluted 
at pleafure. 1. Thirty parts of a mixture of clay, vi¬ 
triol, and fait, to 15 of water. 2. Aqua fortis, colco¬ 
thar, and brine or herring pickle, 15 parts of each to 7-1 
of water. 3. Equal parts of ley and clay. 4. Slaked 
lime, 30 parts to 20 of brine as drong as herring pickle.” 
On the 30th of September, 1793, a houfe ten feet 
fquare, built of dry wood, with two doors and two win¬ 
dows, externally and internally befniearea with tar, filled 
with faggots, tar, and rofin, and having faggots on the 
roof, was fet on fire at botli doors and both windows. 
In a few minutes, it was in a violent blaze ; the mixture, 
No. 1, was then played on it with a little engine ufed by 
M. Von Aken ; in fix minutes the fire was extinguiflied, 
except in the bundles of faggots at the corners, and in 
fome chinks, where it was put out with water : twenty- 
eight kanns of the mixture were ufed. Next, fix bar¬ 
rels of tar in full blaze were quenched with two other 
mixtures, and this fo quickly, that the injeftion was 
fcarcely begun before the fire went out. 
On the 161h of Oftober following, a houfe fixte'en feet 
fquare, condrufted as the former, and covered wdth fag¬ 
gots befmeared with tar, was fired during a heavy gale. 
The mixture, No. 2, was thrown on it with a fyringe having 
an orifice one-fourth of an inch in diameter. The fire was 
inftantaneoufly damped, but the fyringe broke ; which 
accident occafioned a delay of four minutes, and the fire 
was not extinguiflied in lefs than fourteen minutes : lixty 
kanns were ufed. Eighteen barrels tarred within and 
without, in full blaze, were extinguiflied in half a mi¬ 
nute by the mixture No. 4. Thefe experiments are at- 
teded by a number of fpeftators. M. Nydroem concludes 
his account with recommending the following compofi- 
tions for guarding wood againd fire and decay. 1. Com. 
mon fait and green vitriol, equal parts. 2. Common fait 
and colcothar from aqua fortis. The folutions (hould be 
made as drong as podible, and be laid on hot. 
We cannot furnifh fo full an account of M. Von Aken’s 
difeovery, becaufe he waits for a premium, as an induce¬ 
ment to make known his mod effectual preparation. 
The circumdances that have appeared in print refpefting 
it are as follow: In 1790, there happened during the 
night, at Orebro, a conflagration fo violent as to endan¬ 
ger the whole town. M. Von Aken had a dilution of 
vitriol of iron and alum in readinefs, by which he very 
quickly extinguiflied the flames. JHe gave the Patriotic 
Society at Stockholm a particular account of his fuccefs, 
in a memoir which was printed in the tranlaftions of that 
fociety for 1790. He there obferves, that the addition of 
colcothar to the alum and vitriol would be highly advan¬ 
tageous. Since that time, he has exhibited experiments 
on a large fcale at Orebro and Stockholm before the royal 
family, and amid an innumerable concourfe of fpeftators, 
with the mod brilliant fuccefs; and it appears alfo that 
he has in the mean while confiderabiy improved his pre¬ 
paration, It was in vain, however, that lie applied to 
the dates aflembled at Gefle for a reward for his difeo¬ 
very ; and the Patriotic Society opened a fubfeription for 
him without JucccJs! 
M. Von Aken’s defeription of the virtues of his pre¬ 
paration runs in thefe terms: “The preparation which I 
have invented, extinguifiies all combuftible fubdances, as 
tar, pitch, rofin, tallow, oil, fugar, tow, hemp, flax, 
draw. 
