1506 Queries. 
6/6). The former will probably suit the enquirer the better of the 
two. J. W. G. 
393.—Liquid wanted.—It is difficult to obtain a cheap liquid 
whose boiling point occurs between the limits 98° to 100° F. 
Ether is the nearest, and would probably answer, especially if kept 
under the slightest pressure, as its normal B.P. isg6° F. There 
is, however, a variety of petroleum, which boils at exactly 98° F, 
but I am not aware if it is a commercial article. J: WAG: 
393.—Liquid wanted.—In reply to B. O. B., Carbon Disul- 
phide, CS,, comes pretty close to what he asks, as it boils at about 
tro? F., but I should not recommend him to try the experiment, 
as it is very inflammable. J. G. P. VEREKER. 
394.— Pineal Eye.— Perhaps the following note, extracted from 
the Dental Record for April, may interest ‘ Enquirer” :—‘ The 
existence of a third eye in lizards—named by anatomists the 
parietal or pineal eye—is also shown to extend to many others of 
the vertebrates. It was first pointed out in lizards by Graaf and 
Spencer, and has been further studied by M. Francotte in repti- 
lian embryos, in all of which the nerve connections have been 
distinctly traced from the epiphysis at the root of the thalamen 
cephalon to the complete development of the pineal organ ; but in 
each of these the optic nerve which connected the organ with the 
nerve-centres disappears in the adult forms. In the lamprey 
Beard has found it highly developed in a sac under the skin, just 
behind the nose, with a retina, pigment, and the remains of a lens. 
It is interesting to note that the rods of a retina in the parietal eye 
are turned towards the light, while in the paired eyes they are 
turned from it.” 
Queries. 
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must reach him before the 12th of the month. 
395.—Infinite and other Series.—I thank Mr. Bryan for his 
reply (p. 118); but owing to my queries not being sufficiently 
explicit, he has not told me exactly what I want to know. It 
would indeed seem at first sight that an infinite divergent series, 
such as 1—5 + 15—35 + 70—126, etc., ad infinitum, can have 
no calculable finite sum or value whatever. Nevertheless, this very 
