SCIENCE. 
289 
essentially different curves representing heat and light 
must be banished hereafter from text-books. The 
old views on this subject can no longer be maintained 
even by European men of science, who are prepossessed 
in their favor. This result, fulfilling what was almost a 
prophecy when made, a quarter of a century ago, by the 
elder Draper, and, being due largely to means which 
science owes to Mr. Rutherfurd, may, if obtained, be 
most fairly claimed as largely due to the two Americans 
whose names have just been cited. 
ON THE INTIMATE STRUCTURE OF CERTAIN 
MINERAL VEINS* 
Prof. Benjamin Silliman. 
Dr. Sorby, of England, in his classical paper “ On the 
Cavities and Fluidal Inclusions found in Certain Varieties 
of Quartz,” made the sagacious suggestion that certain 
fluidal inclusions observed by him in quartz consisted of 
two fluids, viz., water and probably a liquified gas also. 
An examination has recently been made of a remarkable 
vein stone from a gold vein nown as “ Hunter’s Rest,” 
Arizona. This vein was capped by a black uncrystalline 
rock resembling somewhat hornblend in a compact form. 
But it was seen under the microscope with polarized 
light to be compact tourmaline, a mineral never found 
associated with gold. This black rock which is common 
enough in connection with tin ore, is here abundantly 
coated with gold. But beneath this black capping at a 
very moderate depth, occurs the usual quartz failing of 
gold-bearing veins — the quartz in this vein showing free 
gold in brilliant points, and stains of copper green with 
some pyrite, galena, etc. This quartz seen in thin sec- 
tion under a high power, showed a multitude of fluidal 
cavities, and among them were some which under a high 
power ( y% to 1-1 5-inch) showed distinctly two fluids, one 
of which existed as an inner bubble, and which displayed 
almost constant activity of motion. This second liquid 
was liquified carbonic acid. Thin sections of the vein- 
stone were placed upon a slide for examination. When 
warmed, the carbonic acid expanded and the motion 
ceased, bnt when permitted to become cold, it became 
as active as before. Quartz with gold found in Southern 
California near the Nevada line, is entirely destitute of 
sulphurets, showing that the intervention of iron salts as 
a solvent agent was not necessary in the formation of the 
deposits of gold. 
THE TURQUOISE OF NEW MEXICO* 
Prof. Benjamin Silliman. 
A number of domestic articles have recently been 
found in excavations at Mount Chalchuitl, in Los 
Cerillos, about twenty-two miles southwest of the 
ancient town of Santa Fe. Among these are a 
large stone hammer of the hard hornblendic Andalu- 
site of which the mountains of the country are largely 
formed ; a lamp, a pottery idol, such as are manufactured 
to this day ; a spoon made of shell ; a perpect specimen 
of a pottery dish, and some of the bones of the Pueblos or 
Indian miners, who were killed in 1680 by the fall of a 
large section of Mt. Chalchuitl, which had been under- 
mined by them. These articles had been covered in the 
caverns for 200 years when found. The rocks which 
form Mt. Chalchuitl — the Indian name of the turquoise — 
are distinguished from those of the surrounding and as- 
sociated ranges of the Cerillos by their white color and 
decomposed appearance, closely resembling tuff and 
kaolin, and giving evidence of an extensive and profound 
alteration, due, probably, to the escape through them, at 
this point, of heated vapor of water and perhaps of other 
* Read before the National Academy of Sciences, N. Y., 1880, 1 
vapors or gases, by the action of which the original crys- 
talline structure of the mass has been completely decom- 
posed or metamorphosed, with the production of new 
chemical compounds. Among these the turquoise is the 
most conspicuous and important. In the seams and 
cavities of this yellowish-white and kaolin-like tuffaceous 
rock the torquoise is found in thin veinlets and little balls 
or concretions called “ nuggets,” covered on the exterior 
with a crust of the nearly white tuff, and showing on 
cross fracture the less valued varieties of the gem, more 
rarely offering fine sky-blue stones of higher value for 
ornamental purposes. It is easy to see these blue stains 
in every direction among these decomposed rocks, but the 
turquoise in masses of any commercial value is extremely 
rare, and many tons of the rock may be broken without 
finding a single stone which a jeweller or virtuoso would 
value as a gem. 
That considerable quantities of the turquoise were ob- 
tained can hardly be questioned. The ancient Mexicans 
attached great value to this ornamental stone, as the 
Indians do to this day. The familiar tale of the gift of 
large and costly turquoise by Montezuma to Cortez for 
the Spanish crown, as narrated by Clavigero in his his- 
tory of Mexico, shows the high value attached to this 
gem. It is not known that any other locality in America 
has furnished turquoise in any quantity. The origin of 
the turquoise of Los Cerillos in view of late observations 
is not doubtful. Chemically, it is a hydrous aluminum 
phosphate. Its blue color is due to a variable quantity 
of copper oxide derived from associated rocks. The 
Cerillos turquoise contains 3.81 per cent, of this metal, 
Neglecting this constituent the formula for turquoise re- 
quires : phosphoric acid, 32.6; alumina, 47.0; water, 
20.5. Total, 1 00. 1 . Evidently the decomposition of the 
feldspar of the trachyte has furnished the alumina, while 
the phosphate of lime, which the microscope detects in 
the thin sections of the Cerillos rocks, has furnished the 
phosphoric acid. A little copper is diffused as a consti- 
tuent also of the veins of this region, and hence the color 
which the metal imparts. The inspection of thin sections 
of turquoise by the microscope, with a high power, shows 
the seemingly homogeneous mass of this compact and 
non-crystalline mineral to consist of very minute scales, 
nearly colorless, and having an aggregate polarization, 
and showing a few particles of iron oxide. The rocks in 
which the turquoise occurs are seen by the aid of the 
microscope and polarized light in thin section to be plainly 
only the ruins, as it were, of crystalline trachytes show- 
ing remnants of feldspar crystals, decomposed in part into 
a white kaolin-like substance, with mica, slag and glassy 
grains, quartz, with large fluidal inclosures, looking like 
a secondary product. There is a considerable diversity 
in their looks, but they may all be classed as trachyte- 
tuffs, and are doubtless merely the result of the crystal- 
line rocks of the district along the line of volcanic fissures. 
ON A NEW GENERAL METHOD OF ANALYSIS* 
By Prof. Walcott Gibbs. . 
The process consists essentially in passing a gal- 
vanic current through the solution in such a man- 
ner that a surface of metallic mercury forms the 
cathode, and a plate of platinum the anode. Under 
these circumstances the metal in the solution combines 
with the mercury to form an amalgam. What is new in 
this process is the fact that a number of metals, as for 
example, iron, cobalt, nickel, zinc, cadmium, tin, mercury, 
etc., may be coinpletely removed from the solution so that 
the electro-negative constituent of the roll may be deter- 
mined in the solution by ordinary methods, while the 
metal itself is found by the increase in weight of the mer- 
cury. The extent of the applications of the method and 
its limitations remain to be determined. 
* Read before the National Academy of Sciences, N. Y.,1880, 
