284* C H E M 
weight, and quantity, according to the ftate of the folu- ' 
tion. Cauftic fixed alkalis afford a yellow precipitate, 
more or lefs brown, or of a brick colour, according as 
their caufticity is more perfecf. Ammoniac precipitates 
the nitric mercurial folution, of a grey (late colour, pro¬ 
vided it be of that kind which water cannot decompofe ; 
but the fame fait produces a white precipitate, in a fatu- 
rated folution of mercury, fuch as water can precipitate. 
The precipitates are mere oxyds of mercury, more or lefs 
oxygenated ; they are all reducible without addition, and 
by mere heat in clofed veffels, and all afford pure air 
during their reduction. Thofe which have been preci¬ 
pitated by alkaline carbonats, afford a certain quantity of 
carbonic acid by the aifion of heat. Thofe which, with¬ 
out having been precipitated by carbonats, have been 
merely expofed to the contaff of atmofpherical air, ex¬ 
hibit the fame phenomenon, becaufe they always abforb 
this acid from the atmofphere; a property common to 
all the oxyds of mercury, and even to thofe of feveral 
other metals. The oxyds of mercury, by alkaline inter¬ 
mediums have a property, difcovered by Bayen, which 
mull not be paffed over in filence. They detonate like 
gunpowder, when expofed in an iron-fpoon to a gradual 
heat, after having been triturated in the quantity of half 
a drachm, with fix grains of flowers of fulphur 5 after the 
detonation a violet-coloured powder remains, which may 
be fublimed into cinnabar. 
The fulphuric acid, and the falts into which it enters, 
3 ike wife decompofe nitrat of mercury, on account of the 
llconger affinity of the fulphuric acid to mercury. If 
fulphuric acid, ora folution of fulphats of potafh, foda, 
&c. or of any other fulphuric fait, be poured into a folu¬ 
tion of mercurial nitrat, a whitifh precipitate is formed, 
if the nitric folution be not faturated ; but it is yellower 
in proportion as the nitrat of mercury contains lefs acid, 
and more mercurial 0x5d. This precipitate is fulphat of 
mercury neutralized in the firft inffance, and with excefs. 
ofoxyd in the fecond. Bayen found that it always re¬ 
tains a portion of nitric acid. 
The muriatic acid has no fenfible aftion on mercury, 
though it be one of thofe which have the ftrongeft affinity 
with the oxyd of that metal; but its aftion on mercurial 
oxyd, with which it forms a peculiar neutral fait, is very 
powerful. This combination takes place whenever the 
muriatic acid is brought into contadl with the oxyd, in 
a. ftate of extreme diviffon. If a fmall quantity of mu¬ 
riatic acid be poured on a nitric folution of mercury, 
this acid feizes the oxyd of the metal, and forms a fait 
which'is precipitated in a kind of whitifh coagulum, called 
•vjhite precipitate ; the muriatic falts, fays Dupont, with 
bale of alkali, or of any falin >-terreftrial lubftance, abun¬ 
dantly produce the fame effect, and form befides nitric 
falts, differing according to the nature of the bafe. But 
it mult be obferved, with refpeft to this precipitation, 
that it does not take place when the oxygenated muria¬ 
tic acid is uled; becaufe, though this acid takes the oxyd 
of mercury from the nitric acid, the lalt which it forms 
with that oxyd is very folu'ole in water; whereas the fait 
formed by the common muriatic 3 cid is not at all folu- 
ble. This acid has a ftronger affinity than the fulphuric 
acid with the oxyd of mercury, and occafions the fame 
precipitate in the fulphuric folutions of that metal, as it 
does in the nitric folutions. The compound of muriatic 
acid and oxyd of mercury may exifl in two dates, as we 
have before obferved, according to the Ample or oxyge¬ 
nated flats of the acid ; the latter conltitutes the oxyge¬ 
nated mui iat, or corrofive, and the former the mild, mer¬ 
curial muriat. 
There are feveral procefles for preparing Corrofivefub- 
limate, or corrofive mercurial muriat; in general, equal 
parts of dried mercurial nitrat, decrepitated muriat of 
loda, and calcined lulphat of iron, or white martial vi¬ 
triol, are mixed and put into a matrafs, two-thirds of 
whofe capacity are left empty. This veffel is plunged 
into a fami-bath, and gradually heated till its bottom 
S T R Y. 
becomes of an obfcure red ; the fulphuric acid difengages 
the muriatic acid from the foda ; the latter feparates the 
mercury from the nitrous'acid, from which it takes a 
portion of its oxygen, fo that it becomes oxygenated 
muriatic acid; it then combines with the oxyd of mer¬ 
cury and forms corrofive mercurial muriat, which is fub¬ 
limed in the form of flattened and pointed cryftals to the 
upper part of the matrafs ; the nitric acid being diflipat- 
ed in the form of nitrous gas. The refidue is reddifh or 
brown, and contains oxyd of iron, and fulphat of foda, 
formed by the union of the fulphuric acid with the bale 
of the marine fait. This fait is prepared in the large way 
in Holland, by triturating equal parts of mercury, mu¬ 
riat of foda, and fulphat of iron, together, and expoling 
the mafs to a violent fire. In this operation the oxyd of 
iron, deprived of the llflphuric acid by heat, and highly 
oxygenated, appears to caufe the muriatic acid to pals 
into the oxygenated ftate, fince this iaft only is prefenfr 
in fufficient quantity perfectly to diffolve the mercury 
made ufe of. The corrofive mercurial muriat may like- 
wife be obtained by fublimation, from mixtures of ful¬ 
phat of iron, muriat of foda, and mercurial precipitates, 
by fixed alkalis, or from every kind of oxyd of mercury. 
Boulduc has given a very good procefs for preparing 
corrofive mercurial muriat; but Spielman remarks, that 
it was before defcribed byKunckel, in his Chemical La¬ 
boratory. It confifts in heating equal quantities of ful¬ 
phat of mercury, and decrepitated muriat of foda, in a 
matrafs; the muriat of mercury is volatilized, and the 
refidue confifts of fulphat of foda. Monnet affirms, that 
he has likewile obtained this fait, by treating, in a retort, 
very dry muriat of foda and mercurial oxyd, precipitated 
from its nitrous folution by fixed alkali. In all thefe 
preparations of mercurial corrofive muriat, care mull: be 
taken not to break the fublimatory veffel till it is entirely 
cool, in order to avoid the vapours of the fublimed fair. 
There is another way of preparing the corrofive mercurial 
muriat more readily; it confifts in pouring into a folu¬ 
tion of nitrat of mercury a quantity of oxygenated mu¬ 
riatic acid, and evaporating flowly the mixture. When 
the nitrous acid is difengaged the liquor affords, by 
cooling, cryftals of corrofive mercurial muriat. Chaptal 
propofed to mix the red oxyd of mercury with muriatic 
acid. Or a fuper-oxygenated muriat might be ul’ed; 
with a fait whofe bafe is mercury. 
The fait, called corrofive mercurial muriat, orcorofive 
fublimate, delerves to be carefully attended to by che- 
mifts and phylicians ; it poflefles a great number of pro¬ 
perties which are highly neceflary to be known, and of 
which we ftiall proceed to give a fketch. Its tafte is ex¬ 
ceedingly cauftic : the fmalleft quantity being laid upon 
the tongue, leaves for a very long time an highly difa- 
greeable ftyptic and metallic tafte. This impreifion is 
carried even to the larynx, which it contrafts fpafmodi- 
cally for a long time, efpecially in delicate perfons. The 
adtion of this fait is ftill ftronger on the tunics of thefto- 
mach and the inteftines. When it is applied to thefe for 
any length of time, it corrodes them, and deftroys their 
fubftance, for which reafon it is one of the moll violent 
poifons we know. The caufticity of corrofive mercurial 
muriat appears to depend on the ftate of the mercury, as 
Macquer has very ingenioufly obferved. It cannot be 
attributed to the muriatic acid, as fome authors have 
thought; for the mercury is more than treble the quan¬ 
tity of the acid. On this account the fait renders tyrup 
of violets green, rather than red, according to the ob- 
fervation of Rouelle. The tafte of mercurial muriat is 
befides exceflively ftronger than that of the muriatic acid. 
A drachm of fpirit of fait, diluted with water, may be 
taken with impunity ; whereas a few grains of con olive 
mercurial muriat, dilfolvedin the fame quantity of water, 
would poilbn without remedy. Bucquet thought that 
this extreme ftrength of tafte depended on the combina¬ 
tion of the two bodies, and from thence deduced one of 
his ftrongelt proofs of the law of affinity, whicheftablilhes, 
that 
