has succeeded in accomplishing. At the same time he has a fragment of another mass, still larger than any yet known. which will be called the San-Gregorio Meteoric Iron. Its des cription is as follows:

The San-Gregorio Meteorite.-This immense mass of meteoric iron is situated on the western border of the Mexican Desert, a map of which is given on the next page. Some idea of is form may be had in the accompanying sketch.

6 ft. 6 in.

It measures 6 feet 6 inches in its greatest! length, is 5 feet 6 inches high. and 4 feet thick at its base; on one part of its surface, 1821 is cut with a chisel, and above this date is the following inscription: "Solo dios con un poder este

fierro destruerá, por que en el mondo no habra quien lo puedo deschacer."

It lies within the enclosure of a hacienda, having been hauled to the ranch many years ago by the Spaniards. who thought that it could be made use of as iron for farming utensils. It is said to have fallen quite near its present site. and from its huge bulk and weight, which is calculated to be about five tons, it could not have been transported very far. Nothing more is known of its history. Small specimens were detached by Dr. Butcher, one of which I have examined. I find it to be of the softer meteoric irons, with a specific gravity of 7.84. The fragment I possess is too small for the study of the true character of its Widmannstätian figures.

On analysis, it furnished the following composition:

This San-Gregorio iron makes the fifth that has come under my observation and examination from this famous Mexican locality, the geography of which I will now describe, referring to the accompanying diagram for details.

The Bolson de Mapini or Mexican Desert occupies the western portion of the province of Cohahuila, and the eastern portion of the province of Chihuahua. It is 400 miles from east to west, and 500 miles from north to south, bounded on the north by the river Rio Grande. Some of the villages and haciendas are specified in the diagram, and the numbers 1, 2, 3, &c., are the localities of the different meteoric masses discovered.

No. 1. The locality of the Cohahuila meteorite described by me in this Journal, April, 1854; it is now in the Smithsonian

Institution.

No. 2. The locality of the Cohahuila meteorite of 1868, lescribed by me in this Journal, April, 1870; it is now in the possession of Dr. Butcher.

No. 3. The locality of the San-Gregorio meteorite just described; it is still in the place where it was first observed.

No. 4. The locality of the mass described and figured in my nemoir on meteorites (this Journal, April, 1854), and called he Chihuahua Meteorite; it is still in place at the Hacienda de Conception, 10 miles from Zapata, its greatest height being orty-six inches, breadth thirty-seven, and in the thickest part ight feet three inches in circumference. Signor Urquida calulated its weight to be about four thousand pounds.

No. 5. The locality of a huge meteorite lately discovered, of vhich no specimen has yet been detached, and is said to be arger than any one yet found in that locality.

No. 6. The locality of the large mass described and figured y me in 1854 as the Tucson iron, and now in the Smithsonian Institution at Washington, having a large hole in the center, and

sometimes called the Signet Meteorite, also the Ainsa Meteorite. I do not know its exact weight, but suppose that it must weigh two or three thousand pounds.

The question naturally arises, what can be the cause of the number of meteoric masses in the circumscribed region, and whether each one represents a separate fall? My study of them leads me to the belief that they are the products of two falls. First of all, No. 6, the Signet or Ainsa meteorite, has peculiar physical and chemical characters that separate it entirely from the others. Nos. 1, 2 and 3 I have examined chemically, and find them very closely allied in composition, also in physical properties, as the softness of the iron and freedom from rusty crusts over the exterior; in fact the pieces I have examined were more or less bright on the exterior surface. The Widmannstätien figures I have not had an opportunity to compare, since, with the exception of No. 1, I have had only small pieces that were detached from the surface by a cold chisel, which are unfit for the study of these figures. Thus far in my investigation. there appears strong reasons for supposing that at some epoch, probably far remote, the meteoric masses 1, 2, 3, 4 and 5 were the products of the fall of one meteoric mass, moving from the northeast to the southwest, the smaller masses falling first at 1 and 2, and the larger masses farther on. The distances of these bodies from each other are, from Nos. 1 to 2 about 85 miles, from 2 to 5 about 135 miles, from 5 to 3 about 165 miles, from 3 to 4 about 90 miles. Of course these is no great stress laid upon these deductions, but it would not be surprising if further investigation should sustain this view.

Since my first publication on these meteorites, Burckhardt, of Bonn, has made some observations upon them, but his publications are not within my reach at the present time.

ART. XLIV. On the Iridium compounds analagous to the Ethylen and Protochloride of Platinum Salts;* by Prof. SAMUEL P. SADTLER, Ph.D., Pennsylvania College, Gettysburg, Pa.

AMONG the compounds which we are accustomed to call organo-metallic, those of PtCl, and PtCl, play perhaps the most important part. We can separate them, however, into the two great classes-those where the PtCl, and PtCl, enter by substitution into compound ammonia-atoms, and thus form bases more or less complex, but having still a certain connection; and those where the PtCl, and PtCl, take up organic radicals of different degrees of valence to form saturated compounds.

* Extract from an Inaugural dissertation at the Univ. of Göttingen, April, 1871.

The of this last class, as can be seen, is very wide; one range of the most prominent of these compounds, however, and one which exercised for some time a very considerable influence upon the theoretical views held at that time, is the compound of PtCl2, known as Zeise's salt, and discovered and investigated by him in 1830.

It is not necessary to recount here the controversy which took place between Zeise and Liebig on the subject. Suffice it to say that, by subsequent investigations of Griess and Martius and of Birnbaum, its formula is definitely settled as PtCl,, C2H, + KCl.

2 4

The investigation I now undertook was to see if a similar base of iridium could be prepared. Various considerations, stated at length in my original paper, led me to believe that iridium might not combine exactly as platinum did, in the formation of these salts.

After obtaining the double chloride of iridium and ammonium in the usual way, by decomposing the osmiridium, I made some tests as to the manner of formation of the salt. An attempt to form it by taking the double chloride of iridium and ammonium in solution, and, passing a stream of chlorine through to break up the chloride of ammonium, to then conduct ethylen gas into it, was unsuccessful. The method which suc ceeded most perfectly was to act upon iridium chloride. This was obtained by igniting the double chloride of iridium and ammonium, thus obtaining iridium oxide and metallic iridium, which was then heated with aqua regia in sealed tubes of bohemian glass to 180° or 200°C. This solution of IrCl,, I then treated with absolute alcohol. On adding KCl, and allowing it to crystallize out, I got the greenish-brown crystals of the iridium-ethylen base. On subjecting them to an organic combustion, I obtained as products carbonic acid and water. They burned with a luminous flame, and answered, in short, all the tests applied to Zeise's platinum salt.

Another experiment, to see if ethylen gas would act directly upon the IrCl,, reducing it and uniting at the same time, was unsuccessful.

It will thus be seen, that the only method of preparing the iridium-base is by the reducing action of alcohol on iridium chloride, according to the reaction:

the products of which are iridium-ethylen-protochloride, hydrochloric acid, aldehyde and water.

The purifying of the necessary iridium was found to be a very long and tedious operation, the last traces of platinum.

sticking very pertinaciously to the iridium salt. The processes in use also leave much to be desired in the way of completeness and expedition.

The method selected for separation was the method of Birnbaum, grounded upon the distinct and separate crystallization of the double cyanides of iridium and barium and platinum and barium. To convert the double chlorides of iridium and ammonium, and platinum and ammonium into the double cyanides of iridium and potassium, and platinum and potassium. after trying Wöhler's and Muckle's method and obtaining unsatisfactory results, I had recourse to Martius' method. This consists in mixing the dry impure chloride of iridium and ammonium with powdered cyanide of potassium, and fusing and then taking up with water the fused mass. After working some time with this method, with rather poor results, owing to the high heat required to bring the mass to fusion and the invariable decomposition of the newly formed double cyanides, resulting from the application of such a heat, I modified the method in several particulars. I found, on trying, that the black iridium oxide went very readily into solution in the fused cyanide of potassium. Taking, therefore, the double chloride of iridium and ammonium and igniting it to transform it into the iridium oxide, I proceeded after the following manner. Covering the bottom of the crucible with a bed of powdered KCy, I then added a mixture of KCy and iridium oxide, and exposed it to the flame of the blast-lamp. The fusing cyanide takes up quite readily the metallic oxide, and is soon in calm fusion. A reduction still takes place, but by no means to the extent experienced before. This is occasioned by the strong heat which has to be applied to get the mass into full fusion. Another modification which I then made has some advantages over this just described. It is to bring a few pieces of KCy to full fusion, and then keeping it so, to add a previously prepared mixture of the iridium oxide and finely pulverized cyanide of potassium to it, in small quantities at a time. The advantage here is, that, when the KCy has once been brought to fusion, it can be kept there with a comparatively small flame, and the reduction of the double cyanides does not occur so readily. It is true, that adding the iridium so slowly, the compound is kept in the fused state longer. My experience, however, leads me to prefer this latter plan, and I generally used it as giving the largest yield. Birnbaum's method proper is now used. The solution of the double cyanides, filtered off from any unattacked iridium oxide, contains a tolerably large excess of free KCy. This is destroyed by adding dilute HCl. When neutral, a concentrated solution of copper vitriol is added. The violet-colored precipitate of mixed double cyanides of iridium and platinum with copper is