354 Abstracts of Memoirs. 
The deposits choking up the issue of the water are very extensive, 
and of great thickness. 
Most of the Clermont springs rise to the west and north-west of 
the town. .They are sixteen in number, and compose four groups. 
Some are artificial borings. One group—that of St. Alyr—is re- 
markable for the beautiful incrustations produced by its waters. All 
have deposited enormous quantities of travertin. A natural bridge 
and aqueduct of travertin, nearly 300 feet in total length and 16 
feet wide,.is an interesting example of the nature of this deposit. 
Tt has been about four centuries in forming. The St. Alyr deposits 
are interesting in a mineralogical sense, owing partly to their con- 
dition, and partly to the banded structure of the carbonate of lime, 
more or less coloured by iron oxide. ‘There is also a curious rock, 
consisting of a very hard conglomerate with a calcareous cement, 
combining an infinity of minute water-worn grains and pebbles of 
quartz, pozzuolana, fragments of basalt, and scoriz. The composition 
of the older travertin seems different from that of the modern de- 
posits. The former yields the following analysis :— 
Water . ; é ; ‘ : ; ‘ . 0:800 
Carbonate of lime . : : F ; 5 . A0:224 
Carbonate of magnesia. ; : : : . 26860 
Carbonate of strontian : : j ; ‘ . 0:043 
Peroxide of iron : ; ; ‘ : : . 6-200 
Sulphate of lime d ‘i ; : : pe nates) 
Sub-phosphate of alumina 5 . ; : 4 A5096 
Phosphate of manganese . 0 : 3 : . 0-400 
Crenate and apocrenate of iron . : : . 9000 
Organic matter not nitrogenized : 3 : «| e200) 
Silica ? a : 3 : ; ; j .  9°780 
Loss ‘ : : Z : ; : + 0:05 
100-000 
The more modern rock gives only a trace of carbonate of strontia, 
32 per cent. of carbonate of lime, and 9 per cent. of sulphate of lime. 
Besides these there are many other springs in the valley of the 
Limagne, generally issuing from minute transverse fissures in the 
granite. The total quantity of water is large, but most of the 
separate springs are very small. Arsenic has been detected in them. 
Bromine and iodine, phosphorus and strontian, have also been 
found. There are considerable masses of travertin in their imme- 
diate vicinity. 
On the banks of the Sioule there are numerous groups of springs, 
of which those of Chateauneuf are the most important. Some are 
cold, and several are warm. Neutral bicarbonates are the chief 
contents. The waters being immediately mixed with those of the 
river, there is no opportunity of forming deposits. 
A number of other springs are described by M. Lecoq in various 
parts of the Puy-de-Déme. Some few are sulphurous, but most of 
them yield large quantities of carbonic acid gas and sub-carbonates. - 
The Puy de la Poix yields a considerable quantity of bitumen, espe- 
cially in winter. It is estimated that at least 150 kilométres of 
this substance is thrown out with the water every year, and being 
