Royal Society. 215 
Mn Gray tried wheat would be the fuccels of combinins^ por- 
tions of water by rhe help of brafs rings, ?nd plain pieces of glafs, 
to give them their true figure and rtquifire apertures, and he in- 
ferted them at the ends of tubes of feveral lengths, and he found 
that tho' theie natural lenfes may ferve as eyeglafles, yet when 
uled as objed glaffes, either to telefcopes, or double microfcopes, 
the efifedls will not compenfate the trouble there is in ufing them. 
A Fig. 6. Plate VI. reprefents a imall flat ring of brals, whole 
interior circle mufl not much exceed fo of an inch diameter, and 
be about ~o of an inch thick ; this we may call the frame or cell 
of the glals 5 it mult be prepared for ufe in the following manner. 
Take a fmall globule of quickfilver, and diflolve it in a few 
drops .of u^qimfortis, to which you may add 10 parts of com- 
mon watery dip the end of a ftick in this liquor, and rub the in- 
ward circle of the ring therewith, lo as to acquire a mercurial 
tin^iure, and being wiped dry, be fit for ufe 5 then let it be laid 
on the table, and pour a drop of quickfilver within it, which 
prels gently with the ball of the finger, and it will adhere to 
rhe ring, then cleanle it with a h.-ire's foot, and you will have a 
convex Speculum j take up the ring and Speculum^ carrying it ho- 
rizontally, and lay it on the brims of the hollow cylinder B 3 and 
thus the mercury will become a concave reflecting Speculum^- 
which, from the fmallnels of the fphere, of which it feems to be 
a ie<5tion, may be ufed as a microfcope ; the cylindrical veflel B 
has a icrew-hole at the bottom, by which it is fcrewed to the top 
of the pedeftal CD5 CE FG is the fupporter of the object- 
plate, which may be either railed higher, or let down lower, as 
there is occafion, by the Icrew on the pedeflal j the object plate 
mult be of glafs cemented to the ring G. 
This inltrument, with a little variation, may he made a micro- 
fcope of water, i^ inltead of the ring G, there be only a fmall 
arm with a hole in it to receive a drop of water, and the cylin- 
drical veflel B be either taken away, or Icrewed on with its bot- 
tom upwards, fo as to make an object plate. This will be 
more convenient for viewing the texture of opaque objects, than 
that above delcribed, which is fitter for fluid and tranfparent 
ones. 
A red Colour produced by a fulphureous Spirit and a volatile 
Alcali. Phil. Tranl. N° 228. p. 542. 
THIS fulphureous fpirit is made by diltilling two or three 
pounds of benzoin with a little fand in a retort, ad Sicci- 
tatemy and putting the oil, fpirit and flowers all together into a 
paper 
