C. BOILERS.

27. Building.-Foundation; timber and bolts in walls; window frames; roofs.

28. Boilers.-Stacks and bearers.

29. Boiler Setting.-Foundation; fire-brick work; red-brick work. 30. Castings.-Binders and bolts; grates and frames; floor plates; ash and flue doors; rollers and plates.

31. Pipes.-Main steam pipe; safety valves; stop valves of all kinds (except those furnished by contract with engine); all pipes for steam or water, whether of cast or wrought iron; hangers; bolts ; covering for pipes.

32. Tools.-Pokers; hoes; bars; steam gauges; gauge cocks; gauge glasses.

33. Feed Pumps and Heaters.-Foundations.

D. FURNACES.

34. Producer House.-Foundation; brickwork; iron columns; roof.

35. Producers.-Foundation; red-brick work; fire-brick work. 36. Castings for Producers.-Binders and bolts; plates; hoppers; cooling tubes; grates.

37. Gas Flue.-Foundation; brickwork; man-hole plates.

38. Furnaces.-Foundation; red-brick work; fire-brick work. 39. Castings for Furnaces.-Binders and bolts; plates; flooring; valves; doors; bottom plates and bearers.

40. Tools.-Bars; hoes; hooks; short peels.

41. Charging Machinery.—Cylinders; valves; chains; sheaves; framing at furnaces; long peels.

42. Chimneys.-Foundations; base plates; bolts; bolts and washers; iron shells; brick lining.

E. BUILDING FOR OFFICES AND SHOPS.

43. Building-Foundation; brick walls; roof; window frames; floor; vault with doors.

44. Office.-Fixtures; furniture.

45. Laboratory.-Chemicals; balances; fixtures; furniture. 46. Store Room.-Fittings.

47. Machine Shop.-Engine; boiler and fittings; machine tools; hand tools; vises; shafting and couplings; belts.

VOL. VI.-34

48. Smith Shop.-Forges; anvils; steam hammer; tools. 49. Oil House.-Oil tanks.

F. WATER WORKS.

50. Building.-Foundations; boilers; pumps; pipes to river and to works; tank.

G. ROLLING STOCK.

51. Locomotives.-Ingot cars; bloom cars; dump cars; yard wagons and carts.

H. RAILROADS.

52. Grading.-Wide-gauge railroad trestles and tracks; narrowgauge railroad tracks; coal shoots.

I. SEWERS.

53. Excavations.-Brickwork; pipe supports.

K. SHEDS FOR MATERIALS.

54. Sheds for Brick.-Lime; cement; clay; sand; coke; coal and iron at smith shop.

57. Mechanical Engineering.-Draughtsmen; office expenses; paper; instruments, etc.

58. Civil Engineering.—Draughtsmen; office expenses; paper; instruments, etc.

59. Accounts at Works.-Clerks; office expenses; books; blanks; stationary, etc.

60. Accounts at General Office.-Bookkeeper; clerks; books; blanks; stationery; office expenses, etc.

61. General Office.-Furniture; rent; incidental expenses. 62. Watchman.

O. LEVELLING, ETC.

63. Grading premises, etc.

MISSING ORES OF IRON.

BY PERSIFOR FRAZER, JR., PHILADELPHIA.

(Read at the Amenia Meeting, October, 1877.)

It has been the aim of the writer, by measuring his base line on the territory of theoretical chemistry, to attempt to fix by triangulation certain points within the domain of mineralogy.

As the barest first experiment in this direction, a few of the hydrated oxides of iron have been selected, their theoretical construction reduced to percentage of the constituents into which the ordinary analytical methods would resolve them, and the results compared with actual analyses compiled from the most reliable sources; the accidental errors being as much as possible eliminated. This method seems to be a simple one and one easily pursued, but, as will shortly appear, it is beset with grave difficulties, all of which the writer does not pretend to have satisfactorily surmounted.

In the first place arises the important question, what are we to understand by the hydrated oxides of iron?

In all books of chemistry and lexicons of minerals, the proposition, long ago taught by the earlier chemists, that water might exist in two forms of combination, viz., as water of crystallization or as water of constitution, is tacitly assumed.

There is nothing in the principles of the new chemistry which is opposed to this; for (to carry the mind's eye into the process of construction of the least units into which a definite chemical compound is capable of being divided without losing its characteristic properties), however unlikely it may seem, it is, nevertheless, possible that a given molecule of iron may, under certain conditions of heat, pressure, etc., attract to itself as many molecules of the water in which it is natant as from the relative size, shape, attractive force, etc. of either, it is capable of taking up, and this complex system of associated molecules might oscillate as a physical unit so long as the conditions on which its existence was dependent remained unchanged. Moreover, it is highly probable that the first effect upon such a molecule produced by physical or chemical forces would be to separate it into two or more simple ones of different kinds, while a further application of these forces might rend asunder the bonds of the simpler compounds themselves.

All this is possible; and, to go a step further, it is possible that in a solution containing di-antimony-ter-sulphide,*

[S" Sb""S"-Sb""S"],

and silver sulphide

[Ag'-S"-Ag'],

these two independent molecules swimming in the same menstruum may have such an attraction for each other as to pair together, wherever this is possible, and compound another and more complex (physical) molecule, as represented in the formula of the elder Dana for pyrargyrite. This is possible, provided the conditions are such that no more and no fewer molecules of the one can be retained by the other. But is it likely?

It is not claimed that any unanswerable arguments will be presented here against the existence of molecular affinities, for the object of the paper is a very different and much narrower one. It may be stated, however, that after admitting all the above as possible, a further demand is made on our credulity in the presentation of other compound molecules, consisting of three smaller molecules. Take, for instance, the formula in J. D. Dana's System of Mineralogy for chalcopyrite: Cu,S+FeS+FeS,. Belief in the existence of such a compound physical molecule transcends the power of a not too credulous mind. Suppose, again, that we had a menstruum capable of carrying any given number of molecules. In the first place, is it probable that FeS and FeS, could exist side by side without forming some of those "mixtures" of FeS and FeS, referred to by Prof. Dana under pyrrhotite?

But independently of this objection, how are we to conceive of three separated but saturated molecules so arranging themselves together as to form a complex molecule in which there shall be just one of each of the smaller molecules represented? The graphic statement of this condition of affairs would be as follows:

Cu Cu

Or (Cu)"S"* *

S***Fe":

Fe"S"*** Fe"""S".

To suppose that the molecular attractions would enable the count

one.

less millions of these little molecules floating (or natant) in a solvent to select just one of each for the new compound molecule, would require us also to conceive that either the three molecules were like the three parts of a Chinese puzzle in shape, inasmuch as only one of each would dovetail into the others, and thus form the complete unit, capable of withstanding the motions impressed upon it as an integer of the mineral; or else that the valences, or atom-saturating powers, of the atoms constituting the original constituent molecules were changed so as to offer reciprocal bonds to weld the three into About the former supposition nothing shall be said except this, that owing to the attacks of the strict constructionists upon those who wish to allow a certain play to the scientific imagination in the interpretation of chemical laws, the latter have been completely cowed: nevertheless, although the chemical conservatives are beating a mass of horsehair when they charge any sane person with wishing to represent the actual shape of any molecule by the affinity lines drawn on paper, there must be such a shape; and although the conclusion is not inevitably true, it is nevertheless extremely probable, as Prof. Tyndall suggests in the case of the bar magnet, that, could we subdivide down to the individual molecule, we would find that molecule polarized and exhibiting at opposite extremities the electric forces of opposite signs observed in the polar parts of the magnet. And to apply to this Regnault's* ingenious hypothesis as to the production of all forms in a crystallographic system by modes of axial increment of one of those forms, it becomes exceedingly likely that the molecule of a mineral is a geometrical solid representing one (or more) of the forms of the system in which the mineral crystallizes.

If this be so, we may well ask of Regnault what combination of crystals of (CuS) (chalcocite, crystallizing ortho-rhombic); ferrous sulphide (FeS), known in nature as troilite, and either massive (Dana), or hexagonal (Otto); and pyrite (FeS2, isometric) could produce chalcopyrite (tetragonal), which includes all the constituents in the proportion existing in the sum of the three.

As to the second supposition, viz., that in presence of each other the valences of the elements constituting these supposititious compounds change so as to offer each other, reciprocally, bonds of union to unite the whole into one mass, it leads inevitably to the theory of the composition of minerals, which has been more and more forced upon the

Translation by Betton. Edited by Booth and Faber. Philadelphia, 1852.