SCIENTIFIC SUMMARY. 
103 
It appears to "be quite insoluble in water, so that the addition of a few drops 
of a mineral acid to an aqueous solution of the merest trace of a polyporate 
causes the liquid to become turbid ; it is proposed to make use of this delicate 
reaction in alkalimetry in place of a colour test. The salts of the acid are 
well-defined compounds, some of which, as the polyporates of potash, soda, 
and ammonia, form deep purple-coloured solutions. The empirical formula 
of polyporic acid appears to be C 7 H 9 0 2 . When the potash salt is heated 
to redness with zinc-powder, benzol is formed. 
Platinum Black. — A ready method of preparing the metal in a form which 
exhibits unusually active catalytic properties has been o escribed by Bdttger 
Pharm. Oentralbl.,” xviii. p. 218). He ad d s to a solution of platinic chloride 
-sufficient seignette salt (potassium sodium tartrate), and heats the mixture to 
the boiling point ; a brisk evolution of carbonic acid takes place, and in a 
very short time all the metal separates from the solution ; it has then to be 
washed and dried at a moderate temperature. The finely -divided metal 
prepared in this way readily converts alcohol into acetic acid, and ignites 
illuminating gas when placed in contact with gun-cutton. 
GEOLOGY. 
A New Order of Fossil Reptiles. — The researches of American explorers in 
that apparently inexhaustible mine of palaeontological novelties, the Far West, 
have furnished Professor Marsh with a great portion of the skeleton of a 
huge reptile, which he regards as one of the most remarkable animals yet 
discovered. It was obtained on the eastern flank of the Rocky Mountains, in 
beds which may be regarded as nearly corresponding to the Wealden or else 
■as Upper Jurassic. The animal, which Professor Marsh denominates 
Stegosaurus armatus, probably measured about thirty feet in length, and 
moved mainly by swimming. It possessed teeth with compressed crowns, 
inserted in sockets, and measuring nearly four-and-arhalf inches in length and 
nearly" an inch in greatest diameter. Besides these there are numerous 
cylindrical tooth-like organs, about three inches long and three-fifths of an 
inch in diameter, which were placed in rows, either in thin plates of im- 
perfect bone or in cartilage. These, the author thinks, may prove to be 
dermal spines with the characters of teeth, such as occur in some fishes. 
The body was long and protected by bony’- plates, which appear to have been 
in part supported by the elongated spines of the vertebrae, which are co- 
ossified with the biconcave centra. One of the dermal plates was more than 
three feet long. Professor Marsh regards this remarkable reptile as the type 
of a new order, which he names Stegosauria. — Amer. Journ. of Sci., Dec. 1877. 
New American Jurassic Dinosaurs. — The Dinosaur described by Professor 
Marsh under the name of Titanosaurus montanus, as from the Cretaceous 
deposits of Colorado (see “ Pop. Sci. Rev.,” Oct. 1877, p. 424), is now found 
to belong to a lower geological horizon, and is really from the Upper Jurassic. 
Professor Marsh now changes its name from Titanosaurus to Atlantosaurus , 
the former being preoccupied, and states that additional remains which 
have been obtained, show that it is the type of a distinct family-, which he 
calls Atlantosaundce. The femur of Atlantosaurus montanus is about seven 
