1874.] Technology. 281 
colour and by the alliaceous odour evolved during combustion, he had no dif- 
ficulty in pronouncing that arsenic was present; its presence was experi- 
mentally determined, and its quantity estimated to be o-6o0 per cent of the 
taper, equal to 0°35 grm., or 5°43 grs. of arsenious acid—quite enough to 
poison two people if taken directly in the solid form. The red tapers weighed, 
on an average, about 8-94 grms., and burned seventeen minutes, leaving 
3 milligrms. of ash totally devoid of metallic appearance. Mercury, existing 
as vermillion, was found by Reinsch’s process, and its quantity was afterwards 
carefully determined. The amount of mercuric sulphide ultimately colle@ed, 
washed, and dried, was 1°66 per cent. In one series of experiments the fol- 
lowing results were arrived at—white, yellow, blue, red, and green tapers, 
being experimented upon :— 
White.—Perfe@ly harmless; little ash. 
Yellow.—Harmless ; coloured with chromate of lead; ash, metallic. 
Blue.—Harmless; coloured with ultramarine. 
Red.—Highly poisonous, containing 1°93 per cent of vermillion; the tapers 
very highly coloured ; slight ash. 
Green.—Poisonous ; colour due to arsenic ; metallic ash ; quantity of arsenic 
not determined, but probably about 1 per cent. 
These tapers burned, on an average, twelve minutes, and in number and 
quality were much superior to the first, which were of the spiral character. 
The table is a summary of the results of the examination of the spiral tapers. 
The author afterwards proceeded to consider the effe&t arising, or which might 
arise, from the use of coloured wax tapers, and the inhalation of the vapours 
resulting from their combustion. 
Red. Green. 
Time occupied in burning... .. .. .. «I2mins. 17 mins. 
\WGIEIE 56) G8" “ean “Saad: Mode wee somlOMsE ped guts 2 grms. 
ELCeMtAgelOR WAX arlene 72500 71°30 
Retcentage Of Wicks js es ee sees | 25°44: 26°89 
Weight of wax, pertaper..°.. .. .. 24°85 22°53 
Weight of wick, pertaper.. .. .. . 8°67 8°49 
Percentage of arsenious acid .. .. .. 1°81 
Percentage of vermillion .. .. .. .. 1°66 to 1°93 — 
The, same author submitted a communication on arsenical papers, in the 
course of which he reviewed the theories and cases for and against the alleged 
unhealthiness of rooms papered with hangings having Scheele’s green as one 
of their colouring matters. He mentioned several cases of severe illness, and 
even of death, distin@tly traceable to the inhalation of the green arsenical 
compound used in the preparation of the cheaper kinds of paper-hangings. 
Referring to the opinion expressed by Mr. S. Barber on page 36 of the 
“ Quarterly Journal of Science,” for January, 1874, that mock suns outside 
the sun are an unusual phenomenon, Mr. T. W. Backhouse writes to say this is 
not the case, and that Flammarion’s book, ‘“‘ The Atmosphere,” states that mock 
suns are only on the halo when the sun is low, and that as its altitude 
increases they gradually emerge from it. With reference to the halo of go°, 
which Mr. Barber says he believes is not seen in summer, our correspondent 
Says that, if the halo about go° im diameter is alluded to, he has seen it 
in summer, viz., in 1869, on June 11th and on August roth. Both these days 
were, however, cool, with a maximum temperature of 58°. 
