atmospheric oxygen to convert them into oxides and hydrochloric acid; when they would unite to form silicate of alumina.

Dr. Hayes replied, that, if such a supposition were for a moment entertained, the mixed chlorides could only form hydrochlorates under the conditions, and if the mixed metallic bases were to be oxidized in union, a crystallized silicate of alumina would result, while volcanic ashes under a microscope are either scales with rough imbrications, or feathery forms, such as we every day see in decomposing trachytes and micaceous rocks, water being present.

In reply to the President, Dr. Hayes added, that the chloridic sublimates are not true chlorides usually, but hydrated compounds which do not form solid crystals, being transported in a vesicular state by watery vapor, which, with atmospheric oxygen, is always present in the gases evolved during the most active eruptions; hence true chlorides, excepting common salt, are rarely found.

Dr. A. A. Hayes made the following communication, "On some Points of Chemical Interest, connected with the Manufacture of Ductile Iron by the new Process of H. Bessemer," and exhibited some specimens.

"In calling the attention of the Academy to a part of the process for obtaining nearly pure ductile iron from crude products of the iron-ore furnace, which has of late excited much interest among those engaged in the iron manufacture, it is not my intention to enter upon the economical or technical part of the subject at this time. It is well known that Mr. Bessemer has based his improvements on the startling novelty of making crude iron nearly pure, without the aid of fire from carbonaceous matter. In considering the ordinary mode of refining crude iron, the final operations being performed on crude pig, or on partially refined pig-iron, we have as one of the conditions of success the application of an intense heat, and the presence of more or less atmospheric oxygen, necessary to maintain the required degree of fluidity in the mass of iron, and to burn out the carbon and other impurities present. As the iron loses its carbon and other extraneous substances, it becomes less fusible, and

the workman, stirring the mass as it begins to lose its fluidity, gathers into rough masses the aggregated particles, which are always spherical in general form. From the masses, which are very porous and unequal, a bar of regular form is obtained by the usual means of pressing, or hammering and rolling.

"There is in this process strictly a segregation of particles of pure iron from the crude mass, which, under the agitation of stirring, unite to form rounded aggregations, and the heat of the furnace being increased, the separation of pure iron continues, until the melted impurities alone remain. The change of crude to pure iron is accompanied by the production in part of the impurities which remain; they are not educts. Aside from the loss of carbon in the form of carbonic oxide, the phosphorus and sulphur, which my experiments have proved are always united to the metallic bases of the earths or alkalis, with these bases, burn into oxidized products; while the silicium and a portion of the iron, also oxidized, form the melted slag, or cinder, as an additional foreign matter. To the loss of impurities we must also add the weight of iron burned in forming secondary products, so that, if the operations were performed on crude iron containing ninety-two per cent of pure iron, no more than eightytwo per cent of malleable iron will be obtained. By the method of Bessemer, crude iron in a melted state is exposed in a nearly closed receptacle to jets of air forced into and under the fluid, and it is alleged that such an excess of heat is produced in the process, 'that the metal continues to boil even after the blast has ceased.' The direct statement is made, that the air, dividing into globules, and diffusing itself among the particles of fluid iron, and thus coming in contact at numerous points with the carbon contained in the crude iron, and producing thereby a vivid combustion,' and the same action is implied in other parts of Mr. Bessemer's patent-specification.

"Now it is well known to chemists, that the combustion of the carbon of crude iron cannot take place under the conditions. This carbon exists in gray iron in the allotropic state of graphite, and is not combustible even alone, when exposed highly heated to a current of atmospheric air. We burn it in the laboratory by the application of oxygen in some condensed state only. The proper chemical explanation of this point is a very simple one. Iron, which is a highly combustible body at ordinary temperatures, has its attraction for oxygen enormously increased by the heat of fluidity, and in com

bining with this element, the heat disengaged is ample for carrying the temperature of the mass still higher. A portion of oxide of iron being formed, the mechanical motion imparted by the jets of air favors the contact of the oxide with the carbon, which then burns with the condensed oxygen of the oxide of iron. The products of this combustion, arising from the mingling of oxide of iron and graphitic carbon and pure graphite, are two, pure iron, and carbonic oxide; the former uniting with the mass, the latter escaping as gas, and burning in the atmosphere, or even with any oxide of iron it meets with in the mass. A moment's consideration of the operation shows that the combustion of the iron at the first stage leads to the separation of the carbon as carbonic oxide, and a reduction of the oxide formed to pure iron. Silicium, phosphorus, cyanogen, and sulphur, the bases of the alkaline earths, and interposed slags are oxidized and removed as fusible compounds in the same way, while the pure iron assumes the crystallized state. The combustion of the iron raises the temperature of the acting bodies far above the initial point, while the reduction of the oxide of iron formed diminishes in a corresponding degree this temperature. Were the conditions of the experiment such that the oxide formed from the iron burned was equivalent to converting the carbon into carbonic oxide only, at the moment the oxide of iron became pure iron, then no increase of temperature would be noted, and the cooling influences of the surrounding medium would cool the acting bodies below the initial temperature. Hence, it is essential that more than an equivalent of iron should be burned, and a loss of this substance must take place, so that the operation of purification by the new process is carried on by substituting iron as fuel for carbon consumed in the ordinary process. Assuming six pounds of carbon to exist in a sample of crude iron containing ninety-two pounds of pure iron in one hundred pounds, then twenty-eight pounds of iron must be burned to oxide, and the six pounds of carbon will exactly reproduce the twenty-eight pounds of iron, leaving ninety-four parts of iron deprived of carbon. But the practical result differs from this statement, inasmuch as a positive loss of at least ten pounds of iron occurs; and in explaining the increased elevation of temperature, we neglect that portion of the iron which, having been burned. and again reduced, adds to the mass, and keep in view the effect of the combustion of ten pounds of iron lost in the operation at the high temperature attained. Accurately, some addition to the temperature

is made by the combustion of other bodies present besides carbonic oxide, but there are also sources of expenditure; leaving as useful effect the amount of heat generated by ten pounds of iron burned, from every one hundred pounds of melted iron taken.

"I believe this combustion, going on momentarily with the reduction of the oxide, is sufficient to afford the excess of heat required to maintain the temperature of the mass of iron above the initial temperature for the short time of thirty or forty minutes, during which the conversion takes place in a nearly closed vessel.

"The other point in this connection is the condition of the pure iron at the moment of its conversion. As this is most important to a correct conception of the practical bearing of the method, it was deemed necessary to describe briefly the ordinary mode of puddling iron, and reference is now made to that part where it is stated, that, as the iron becomes pure, it is less fusible.

6

6

"In ordinary, this less fusible part is gathered,' and forms 'puddle-balls'; if not thus removed, and time sufficient were allowed, the whole charge would become consolidated, and could not be removed. In the new method, the jets of air agitate or boil' the fluid iron, and yet this solidification does not proceed, and it has been assumed that the acting temperature is so high that the pure iron becomes fluid. No evidence has been presented to sustain this assumption, and it has been shown above, that there is no source of heat present adequate to cause such fluidity. All the specimens of a suite illustrating the manufacture, prepared under the eye of Mr. Bessemer, show that such heat of fluidity is unnecessary." (Dr. Hayes exhibited these specimens, which illustrated, step by step, the conversion of crude iron into pure iron, and the subsequent production of the interwoven particles forming wrought-iron, and the most finished specimens of laminated sheets.)

"These specimens prove that the molten mass of pure iron is not a liquid iron, but a semi-fluid composed of crystals of pure iron, which, in accordance with the laws of crystallization, have withdrawn from the fluid, merely wet by the fluid iron present, and rendered pultaceous by the carbonic oxide gas entangled. This physical condition of the iron is represented by particles of hail mixed with a small proportion of water, or more exactly by the mixture of crystals of sugar and concentrated sirup, as it is filled into the forms; such a mass will flow and take sharp impressions in the moulds, while its

texture on cooling is highly crystalline and porous. Although the iron in this state is as pure chemically as any bar-iron, its mechanical state does not assimilate it to malleable iron, and the ingots rarely present the compactness of cast-iron of the coarser qualities. A careful examination of the specimens suggests the conclusion, that much of the character of fluidity is also due to the presence of the engaged carbonic oxide, which, like any gas disengaging from a dough-like semi-solid, causes it to flow.

"This mechanical constitution of the pure iron removes the difficulty which every iron-master must have conceived to exist, in the descriptions of the new method heretofore published, and it will be seen that the effects produced in the old and new process are strikingly similar; while the fuel in the one case is iron, in the other the ordinary coke or coal. In removing the iron from the furnace, the puddler depends on forming a rude porous aggregate, while Mr. Bessemer, by a refined mechanical agitation, converts the whole into a semi-solid, crystalline mass, full of gas-bubbles, which flows from an inverted vessel, and takes the forms of the moulds.".

Mr. Charles Jackson expressed a doubt as to the practical value of the new process, and adduced the significant fact, that it had not in the least affected the price of iron in the market, nor the value of iron-works.

Dr. Hayes rejoined, that he had presented to the Academy only the interesting chemical points, avoiding the economical bearing of the discovery. He was, however, prepared to discuss this fact, in view of its importance to the English, rather than to the American manufacturer.

Professor Gray presented, in the name of Dr. Engelmann, the following

"Corrections and Additions to the Synopsis of the Cactaceae of the United States.

"On p. 279, the var. minor of Cereus dasyacanthus should be cancelled, and after C. longisetus, p. 280, the following added:

"94. C. RETTERI, E. in B. C. R.: ovato-cylindricus, 10-12 costatus; areolis ovato-orbiculatis; aculeis e basi bulbosa subulatis-rubellis apice obscuris exterioribus 10-15, interioribus 2-5 robustioribus