392 
organic matters contained in the air. Some time ago the author 
in connection with Mr. Wanklyn and Mr. Smith, found that 
the smallest traces of nitrogenous organic matter in water 
could be detected by converting the nitrogen of the organic 
matter into ammonia and estimating the latter with the 
Nessler test. It occurred to the experimentors that the 
process might be extended to the investigation of the air by 
washing it with water. But Mr. Chapman found the opera- 
tion of washing the air more difficult than he had expected. 
It seemed the most obvious method to draw air through water, 
or through some other medium which would have afterwards 
to be washed with water. The absorption by water alone 
proved insufficient. Filters of cotton wool and gun cotton 
acted very well; but neither of the two materials could be 
obtained free from traces of nitrogenous substances. Asbestos 
seemed to be sufficiently good ; but the preparatory treatment it 
has to undergo before its use in the experiment, is too trouble- 
some. Lastly, finely powdered pumice-stone was tried as a 
filtering medium and was found satisfactory in all respects. It 
has to be heated to redness before it is employed and is then 
moistened with some water spread over coarser pieces of pumice, 
which rest on wire gauze fitted intoa funnel. The funnel is con- 
nected with one neck of a Wolfe’s bottle, whilst the other neck 
is joined to an aspirator. When a sufficient quantity of air— 
say 100 litres—has been drawn through the apparatus, then a 
pumice is transferred to a retort which contains water freed 
from ammonia and organic matters and the operation is now 
proceeded with exactly as if it were an estimation of nitrogenous 
organic matter in a sample of water. By this method Mr. 
Chapman found that the air of crowded rooms contains sus- 
pended fixed organic particles, as well as volatile bases. The 
first can be removed by filtration through cotton wool, the 
latter pass through the filter and when conducted into water can 
be detected therein. Air collected from the neighbourhood of a 
sewer contained notable quantities of those volatile bases. The 
author thinks it would be of interest to investigate by the above- 
described method the air in hospitals, fever wards and the 
like places. With respect to the examination of the volatile bases 
occurring in the air, Dr. Mills suggested that the charcoal out of 
the ‘‘Stenhouse air filter” might furnish a good means for 
collecting those bases.—In another paper Mr. Chapman 
communicated some new reactions of alcohols. Amylic alcohol, 
as commonly obtained, consists of two liquids, one rotating the 
polarised ray, the other not. The two may be separated by 
distilling the mixture from soda, calcic chloride, &c. The non- 
rotating alcohol is retained, the rotating distills over. But 
by repeated distillations it was found that the rotating 
alcohol is converted into the non-rotating by the very 
treatment employed to separate the two. No difference in 
the physical properties of the two alcohols is perceptible. The 
compounds of the non-rotating liquid do not turn the ray of 
polarised light ; those of the rotating do and that in an opposite 
direction to the original alcohol. These facts seem to indicate 
that the internal structure of organic compounds is not so perma- 
nent as the habit is of thinking them. Another observation 
Mr. Chapman made whilst pursuing these experiments was, that 
caustic soda is not merely unable to dry alcohol, as is well known, 
but that it actually moistens it. On proper investigation, it 
turned out that the sodium replaces the hydrogen of the alcohol, 
whilst the displaced hydrogen takes the place of the sodium in 
the caustic soda and thus produces water. Referring to this 
latter observation, the president remarked that it confirmed 
the idea of a double decomposition taking place when potas- 
sic hydrate is dissolved in alcohol, an idea derived from 
the well-known reaction of carbonic action on a solu- 
tion of potassic hydrate in alcohol, whereby ethylo-potassic 
carbonate as well as potassic carbonate is formed. — Mr. 
Perkin exhibited a modification of Berthelot’s method for the 
synthesis of hydric cyanide (prussic acid) by direct union 
of acetylene and nitrogen under the influence of the electric 
spark. Mr. Perkin takes advantage of the fact that 
nearly all the hydro-carbons, when submitted in the state 
of vapour to the action of the spark, yield more or less ace- 
tylene. Nitrogen was caused to bubble through benzole, then 
to pass through a globe in which the spark was discharged 
and thence into a solution of silver. Even after a few 
seconds, abundant evidence of the formation of hydric cyanide 
was obtained. Hydric cyanide is further produced when the 
spark is discharged in a mixture of ammonia-gas and ether 
vapour. If, however, nitrogen instead of ammonia is employed, 
NATURE 
[ Feb. 10, 1870 
no prussic acid is formed. Mr. Perkin’s modification of 
Berthelot’s method is well adapted for purposes of lecture 
demonstration. 
Royal Geographical Society, January 24 —Sir R. Murchison, 
president, in the chair. A letter from Mr. Hayward detailing his 
plans of reaching the Pamir Steppe, by way of Ghilghit, was 
read. He expected to winter in Ghilghit and hoped to be at 
Lake Karakol next May; he proposed to thoroughly lay down 
the positions of the Pamir Steppe and the basin of the Jaxartes. 
An account of Easter Island, or Rapa Nui, by Mr. Palmer, 
R.N., was then read. The island lies in 27° 8’ 46” S., long. 
109° 24’ 36” W., about 1,000 miles from Pitcairn. It is volcanic 
and contains several extinct craters, the highest point being 
1,100 to 1,200 feet high. The principal craters are Te Rana 
Kau, the depth of which is 700 feet; Te Rano Hau, whence 
came the tufa of which the hats or crowns of the images are 
made; and Te Rana Otu Iti, where the images were sculptured 
of grey lava. There is no water, save in pools, which are 
26 feet deep and one spring, mineral, but potable. The coast 
is ironbound, without harbours. The character of the natives 
has been much improved by the teaching of the Jesuit Fathers 
and they now are scrupulously honest. They are perfectly idle, 
content to starve rather than work; number about 900—600 
women to 300 men and will probably, ere long, die out. They 
make and sell well-carved wooden figures, with eyeballs of 
obsidian, ornamented with double-headed ‘‘aronies,” or birds— 
and other figures. They are described by all visitors as a tall, 
almost white, race ; the women handsomer than those of the 
Marquesas. They are not idolatrous, but believe in a Great 
Spirit. The dead, swathed in grass, are laid on platforms, 
heads to seaward. They have a tradition that they came from 
Oparo. The platform for the images faced the sea, supported 
by a stone wall seven or eight yards high, built of dry stones six 
feet in length; the platform was 100 paces long and _ thirty 
feet deep, terminating landwards in a step three feet high. It 
was strewn with bones; all the images had been thrown down. 
Near that, on an area paved with large stones, stood a pillar of 
red tufa, six feet high, on which were two skulls, apparently 
twelve or fourteen years old. A place of cremation was near 
this. The images amount to several hundreds, some unfinished. 
In the crater of Otu Iti they vary in size from thirty feet (of which 
the head measures two-thirds) to five feet. They are marked 
by excessive shortness of the upper lip ; the eyeballs, of obsidian, 
are lost; the ears display very long pendant lobes ; each image 
has its own name; some have “ hats” or crowns, some have the 
heads cut flat to receive them ; the tools seem to have been long 
boulders ground down with obsidian—only one specimen was 
found. The paper was illustrated by numerous drawings made 
on the spot and enlarged pictures taken from them. Mr. 
Markham pointed out the resemblance between these remains 
and the Imarra works in the vicinity of Lake Titicaca, in Peru 
and advocated the theory that this island had been a stepping- 
stone for the successive arrivals of immigrants into Peru and 
perhaps revered as a holy isle whither the Incas sent ships. 
The Peruvian images were dispersed like those of Easter Island, 
as though walking through the country; the present islanders 
were simply Polynesians and probably not descendants of the 
sculptor-race. Mr. Franks pointed out the resemblance of some 
peculiarities in the wooden figures now made and the stone 
images ; at the same time the wocden figures brought home by 
Cook and now in the Museum, differed materially from those 
brought in 1840—the change of style, therefore, would not imply 
a change of race. The want of forest timber might have 
occasioned the employment of the soft volcanic tufa and a 
long lapse of time would account for the numbers of images 
found. Sir G. Grey stated that all Polynesians were addicted to 
carving—if the wooden figures carved in New Zealand had not 
decayed there would be now thousands of them ; there were in 
these islands traditions of stone figures brought from other islands. 
Mr. Palmer said, in reply, that he had not formed any theories on 
the subject ; but only recorded what he saw ; the people had all 
been withdrawn to the settlement in consequence of the Peruvians 
having kidnapped some hundreds to work the guano deposits. 
Anthropological Society of London, February 1.—Cap- 
tain Bedford Pim, R.N., V.P., in the chair, ‘‘On the negro 
slaves in Turkey,” by Major Frederick Millengen, F.R.G.S. 
The author exposed first the particulars connected with the sale 
of negro slaves in Mussulman countries, then described the con- 
dition of negroes in Turkey and concluded by some general 
