260 Literary and Philofophical Intelligence. 
corn from yellow flies and other infetts.— 
4. For fecuring turnips from the ravage 
of flies. The dwarit elder appears to ex- 
hale a much more fcetid fmell than the 
common elder, and therefore fhould be 
preferred. 
It has lately been afferted, in the Me- 
dical Journal of London, with confidence, 
that the action of contagious miaf{mata, 
in the cafe of malignant fevers, &c. is ne- 
ceflarily limited to very fhort diftances, as 
a few feet—to produce caution on this 
head, two well-authenticated fa&ts are ad- 
duced:—At the Old Bailey, in 1750, 
nearly one hundred prifoners were tried, 
who, during the fitting of the court, were 
confined together in very fimall apart- 
ments. When brought into court, the 
windows oppofite to the bench where the 
judges fat were thrown open: the people 
on the left, to which fide the wind blew, 
were infegted with the jail-fever, and 
above forty died, among whom were the 
lord mayor, twd judges, one alderman, 
and feveral inferior officers of the court. 
' ‘The lord chief juftice and the recorder, 
who fat on the lord mayor’s right-hand, 
efcaped, as did the London jury, who fat 
on the fame fide of the court, whilft many 
of the Middlefex jury, who were placed 
oppofite to them, caught the fever, and 
died. At the Oxford affizes, 1577, the 
effiuvia arifing from the prifoners, who 
were themfelves not ill, infe€ted a great 
part of the court with a peftilential fever, 
of which three hundred perfons died. 
Sir. GEORGE PAUL, noted for his con- 
neétion with the prifon at Gloucefter, has 
invented a new method of ventilating 
jails, hofpitals, &c. The fame may be ap- 
plied with perfect facility to fhips, and 
even to the clearing of aflembly-rooms, 
&c. from the impure air contracted by the 
mecting of large companies. 
In the new edition of the Pharmaco- 
paia Edinburgenfis, which will fhortly 
appear, the nomenclature introduced by 
the French chemifts is adopted in its fulleft 
extent. 
The Lichen Icelandicus has been fome 
years in confiderable repute on the Conti- 
nent, as aremedy in pulmonary complaints, 
and asa reftorative in difeafes of exhauf- 
tion—a Ruffian has lately obtained a pa- 
tent for making bread of it; and M. 
REGNAULT, of Paris, recommends it to 
be taken, in the form of jelly, by boiling 
fix ounces of lichen in as many pints of 
fpring-water for an hour or more, then 
evaporating the deceétion, with the addi- 
tion of fix ounces. of refined fugar, to the 
- Gonfiftence of jelly, This is to be taken in 
[A pril 1, 
the quantity cf three or four ounces of 
more daily. ~ 
M. FisHer has invented an economical 
mode of preparing the red oxide of mer- 
cury, which is as follows:—** Let any 
quantity of quickfilver be diffolved in a 
fuffcient quantity of nitric acid, and the 
fulution evaporated to drynefs: with the* 
falt thus obtained, a further portion of 
guickfilver, nearly equal to the quantity 
at firft employed, is to be triturated, with 
the addition of water enough to form a 
pafte, till the quickfilver entirely difap- 
pears. ‘The moift mafs is then to be 
gently dried, and expoled to a gradual heat 
in aretort. Ina few minutes it aflumes a 
red colour, and, when cooled, it is ob- 
tained in the ftate of fine powder.” 
Dr. MitrcuHitt, of New York, in 
making fome experiments with the ther- 
mometer, difcovered that black bodies did 
not abforb the white or undecompofed rays 
of light; but did, in a confiderable degree, 
decompofe them, and refleét the coloured 
light of all the hues to the organ of vi-. 
fion. He faw the prifmatic colours plainly, 
on the filaments of black filk; on the 
black briftles of fwine. Afterwards a 
black hat was expofed to the rays of the 
fun, and rainbow-cclours were reflected 
from the fides of the fur and hairs. Simi- 
lar refults were obtained from experi- 
ments on black leather boots ; on a black- 
paper {nuff-box, &c. &c. Hence he con- 
cludes, that, though it has been ufual to 
define white to be the prefence of all co- 
lours, and black their abfence; yet it 
would be more correét to fay, that waite 
is the refleétion of folar rays in their com- 
pound ‘tate, while black is the refle&tion of 
the fame rays, after an indefinitely {mall 
refolution or decompofition: or, white is 
the abfence of all diftin&t and fenfible co- 
lours, and Slack is the prefence of all: 
or again, white is the effect of heteroge- 
neous, and black of homogeneous, light. 
M. 'THENARD’s Experiments on the 
Zoonic acid prove that it 1s nothing more 
than acetous acid holding in folution 
an animal matter that approaches nearly 
to the ftate of cil. This gives the acid 
the property of precipitating different mes 
tallic falts, and efpecially thofe of mercury 
and Jead. 
The Rev. Burertss ALuison has 
given, in the American Philofophical 
Tranfactions, a defcription of a newly- 
invented globe time-piece, by which the - 
following problems may be readily work~ 
ed :—1. To find the hour and minute of 
the day.—z. To find, with great dccuracy, 
the time of funerifing and 4un-fetting in 
: } | _ every 
