2i6 MEMOIRS?/ the 
paper filtre, the fpirit comes firfl thro\ You may put two parts 
of this fpirit to one of fpirit of lal armoniac, or urine, ^c. and 
fhaking the- glals or bottle, it will become red in a moment, tho' 
both the luiuors were clear before, and the more the glafs is 
ihaken, the deeper will the red be ^ it produces this effect with- 
out any efferveicencc 5 this experiment may perhaps be ufeful m 
explaining languification. 
A SlackiJJj Stone /;/ Shropfhire yielding Pitch, Tar and Oil 5 
by Mr, Martm Ele. Phil. Tranf. N° 228. p. 544.. 
IN 'Brofely^ Sentky, Titchford^ and other adjacent places in 
Shropjhire-, there lies over moft of the coal-pits, or mines, a 
Stratum or layer of a blackifli rock, or ftone, of fome thicknels, 
which is porous, and contains in it great quantities of bituminous 
matter. This ftone, being brought to the work-houfe, is ground 
fmall by horlc-mills, fuch as are ufed for grinding flints to make 
glais of; the powder is thrown into great coppers of water, 
where, by boiling, the bituminous matter is fepararcd from the 
ftony or gritty part, this Jaft finking to the bottom, the other 
I'wimming at the top of the water. This bituminous fubftance 
being gathered together, and evaporated, becomes of the con- 
fiftencc of pitch, and this, by means of an oil, diftilled from the 
fame ftone, and mixed therewith, becomes thinner, or like tar, 
Thefe fubftances are found to exceed common pitch and tar, in 
that they do not crack, but keep always black and fofr, by 
which they may be lerviceable to prevent the worms from hurt- 
ing fhips pitched therewith. The oil may be uled for oil of 
petre or turpentine, and it has been tried in aches or pains. 
1'be 'Uiffci'iion of a Scallop; by "Dr. Lifter. Phil. Tranf. 
N° 222. p. 567. Tran/lated from the Latin. 
IN the firft place Dr. Lifter obferved the Cardo, or hinge of 
the concave fliell to be gently bent and laid on the other of 
the plain fliell, both which were firmly conneficd together by a 
cartilage ; alfo in the very middle of the hinge there was another 
very black and ftrong cartilage ; hence arifes that wonderful con- 
ftriciive force it is endued with, and perhaps the power of moving 
the plain fliell, like an oar, to row by; which the ancients have 
often mentioned as peculiar to this fliell-fifh. Upon opening the 
ihells, he obferved the following particulars; to the right hand 
and under the hinge a cowled mouth like an oyfter; this cowl is 
made up by the concourfe of the external '^rancbice or gills, 
which arc mufcular, and encompafs the animal entirely from the 
head 
