ing the borders of the western or Erie portion of the basin, we should expect beach lines and wave action generally at any horizon above the present level of Lake Erie to be less conspicuous in the former than in the latter district. The fact that the raised beaches of the Lake Erie basin occur at only a few levels apparently indicates that the lake dropped rapidly from the level of one beach to that of the next lower, for had the interval of lowering been prolonged beachlets of considerable strength would have been formed at various levels.*

In the district east from the Lockport moraine we should expect wave action to be pronounced in but a narrow zone, even if the ice-sheet had withdrawn before the Crittenden beach was formed. If it did not withdraw until after that beach was formed we should expect, at most, but an ill defined zone of wave action. Upon examining the district eastward from northwestern Genesee county (where the Lockport moraine and the Crittenden beach intersect) we found a narrow belt at about the level of the Crittenden beach where the drift

*In studying the effects of the waves the depth to which effective wave action extends becomes a question of considerable importance. The depth of lowest wave action is, of course, related to the magnitude of the waves and this to the size of the water body, being greater on the ocean than on our great lakes. The great lakes are, or were, each of the same general order of magnitude, and their wave work may properly be compared. Prof. Shaler and Mr. Gilbert have examined jointly a district at the eastern end of Lake Ontario with this subject in mind. Prof. Shaler has published the following statement of results:

Exposed off shore Deposits.-It might be supposed that wherever in relatively recent times a beach now elevated has been formed the surface of the earth below its level would retain some indications that it had been beneath the water. It might reasonably be expected that a submergence which had endured long enough to permit the formation of characteristic beach accumulation would have sufficed for the formation of a tolerably enduring marine deposit lying off shore."

"At the outset of my studies of the elevated beaches of the Atlantic coast, the remains of which are of a rather fragmentary nature, I was led to doubt the verity of the indications by the absence of these marine deposits from the surface of the lower lying land. To test the matter I resorted to the country lying on the east and south of Lake Ontario, where the well preserved Iroquois beach indubitably proves long continued sojourn of the waters at a considerable height above their present level. I found that below the plain of the beach the general surface of the country showed no distinct indications that it had been submerged. In fact I was unable to find any criteria which would enable me to discriminate the areas below and above the ancient sea-margin. It must be believed that where the submergence has endured for a long time a certain amount of sediments would be laid down in the off shore district and that the period required for the formation of such a beach as that last mentioned should have brought about a considerable accumulation of clay. It seems, however, likely that in a few thousand years of exposure such clay deposits would, by the down bearing action of the rain waters, be carried down into the earth or washed away into the streams." (Bull. G. S. A., vol. vi, pp. 151–152.)

Mr. Gilbert's testimony is as follows: "It seems to us that after going 50 feet below the lowest member of the Iroquois series there was practically no modification of the drift forms; and while riding over the drift hills the only indication we could see of the lake occupancy was a loamy deposit from a few inches to a few feet in thickness which could often be distinguished between the soil proper and the unmodified drift. The evident inference was that the water had fallen from one level to the other in a very short time." (Personal correspondence.)

forms seem to have been somewhat modified by the action of waves or currents of water. This is considered a possible lake level or perhaps a lake outlet. There is a large amount of gravelly drift in this belt but so far as discovered it is not arranged in beach lines, the surface being either plane or having a gentle undulation as if the drift knolls had suffered reduction or modification by waves or currents. This gravelly drift occupies usually a breadth of two or three miles. In places it occupies the entire interval between the Lockport moraine and the drumlin belt which lies north of it. At the southern end of these drumlins for a few miles west from the Genesee river, knolls and ridges of morainic type occur, and these are frequently bordered by gravelly aprons or delta-like accumulations; near the western end of the drumlin belt, also in the vicinity of Careyville, Genesee county, there is a gravel plain dotted with basins. These features are thought to indicate that the ice-sheet for a time occupied the drumlin area and country to the north but did not extend so far south as to completely bar out the water from the Lake Erie basin. It may, at times, have covered the gravelly belt while at other times it may have afforded an eastward outlet along the south border of the ice-sheet.*

Still later the ice-sheet halted along a line just north of the drumlin belt, as is indicated by a small moraine which follows quite closely the line of the Erie canal from Rochester westward to Albion. (Its course has not been determined west from Albion.) South from this moraine there are, in the vicinity of the Genesee valley, quite heavy deposits of sand capping the drumlins and the plains among them. The sand extends north to the south border of this moraine but does not overspread it. This limitation of the sand is thought to be an indication that the ice-sheet was occupying the moraine at that time. The phenomena indicate that the ice-sheet held a narrow body of water in the Genesee valley and this may also have had an extension along the ice front some distance east and west, between this moraine and the elevated country to the south. It is not yet known whether it afforded, at that time, an outlet to the Mohawk valley.

The district between the Lockport moraine and the Iroquois beach presents other features which, when fully understood, promise to throw light upon the relation of the ice-sheet to the lake. We take time to mention the features of but one locality. North from the western end of the drumlin belt

*Prof. H. L. Fairchild has recently published the opinion (this Journal, vol. xlix, Feb., 1895, pp. 156-157), that there was a temporary outlet from the eastern end of the Lake Erie basin through Seneca Lake to the Susquehanna, near Elmira. Prof. Fairchild's studies, now in progress, promise to shed light upon this and other questions connected with the lake outlets and the descent of the lake from the Crittenden to the Iroquois beach.

there is, in southwestern Orleans county, a peculiar system of gravelly ridges and knolls. The ridges vary in type, some being low like bars or beaches of a lake and presenting much the appearance of lake strands. Others are 40-50 feet or more in height and resemble eskers. The smaller ridges have a tendency to east to west trend and are best developed along the watershed north of Oak Orchard creek. With a few exceptions the esker-like ridges have, like the drumlins, a N.E. -S.W. trend, probably conforming nearly to the line of icemovement. Besides the ridges there are clusters of sharp gravelly knolls of kame-like type 30-40, and occasionally 6075 feet, in height. They are usually strewn more thickly with bowlders than the bordering district, a feature which, taken in connection with their topography, strongly supports the view that they are morainic. The diversified features, combining those of lake ridges with ridges of glacial type, lead us to anticipate that they will throw much light upon the method of departure of the ice-sheet, but as yet their significance is not clear.

The Lake Outlets.-My former paper discusses the outlets at the time of the higher stages of the lake which occupied the Lake Erie basin. The evidence is clear that during the formation of the upper two beaches an outlet was found to the Wabash past Ft. Wayne, Indiana. At the time the third or Belmore beach was formed (and its probable continuation, the Sheridan beach) this outlet had been abandoned. It is thought that the ice-sheet had retreated so far from the Huron and Michigan basins as to open a lower outlet through these basins than that past Ft. Wayne. It seems improbable that an eastward outlet was then open, for the district south of Lake Ontario was apparently still occupied by the ice-sheet. It is evident that no outlet to the east could have existed until the ice-sheet had withdrawn from the Lockport moraine sufficiently for a passage eastward along its southern margin. If my interpretations are correct the Crittenden beach had been for a long time occupied by the lake before an eastward outlet was opened, a time sufficient, not only for the Lockport moraine, but for several other slightly older minor moraines to be formed. During that time the lake, in all probability, discharged westward through the Huron and Michigan basins past Chicago. When the gates to the eastward were opened by the withdrawal of the ice-sheet there was probably a brief period in which the lake discharged through the Seneca valley into the Susquehanna. But soon the lower outlet by the Mohawk was opened and the lake fell rapidly to that level, leaving but feeble traces of beach or wave action in its intermediate stages.

Denmark, Iowa, March, 1895.

ART. II.-On some Compounds containing Lead and extra Iodine; by II. L. WELLS.

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ABOUT two years ago the writer described the double salts of lead tetrachloride, (NH), PbCl ̧, K ̧PыСl, Rb,PbCl and CsPbCl, and upon attempting to prepare the corresponding bromides and iodides, an entirely different kind of double salts was discovered. These peculiar salts were K,Pb,Br.. 4II, and K,Pb,I. 4H2O. They are remarkable in containing but a single atom of extra halogen in the formula as given above, and they apparently correspond to no previously known compound. I was unable to obtain, with the alkali metals, any bromides or iodides corresponding to the chlorides, but it is interesting to notice that Classen and Zahorskit have obtained such salts with quinoline, (C,H,NH),PbBr, and (C,H,NH),PыIS.

The isolation of lead tetrachloride by Friedrich and the discovery of lead tetra-acetate, Pb(CH.CO), by Hutchinson and Pollard were very interesting additions to our knowledge of the compounds of tetravalent lead. These articles appeared almost simultaneously with that of Classen and Zahorski which has been referred to above, and with my own work mentioned at the beginning of this article.

As a sequence to my former investigations, it has seemed to be desirable to reinvestigate two previously described compounds containing lead and extra iodine, because it seemed possible that a further study of them might throw some light upon the nature of the curious salt, K,Pb,I,. 4H2O.

Johnson's Salt.-By mixing a hot, concentrated alcoholic solution of potassium triiodide with a saturated solution of lead acetate in boiling alcohol, filtering off the small precipitate thus produced and cooling, G. S. Johnson** obtained a crystalline substance to which he gave the formula, Pb,C,,H,, OK,I,,. Concerning this he remarks, "The formation of a rational formula has at present baffled all my endeavors."

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Johnson also obtained the salt by recrystallization from alcohol and by evaporating the mother-liquor over sulphuric acid, but there is no evidence that he analyzed more than one sample of it. He does not give the quantities used in making his preparation.

*This Journal, xlvi, 180, 1893.

Zeitschr. für anorg. Chem., 4, 107, 1893.

This Journal, xlvi, 190, 1893.

Classen and Zahorski gave a formula of different type, 5NH,Cl. 2PbC14, to the double ammonium chloride. It seems certain from analogy, from Friedrich's results and from my own work, that their product was contaminated with ammonium chloride. Berichte, 26, 1434, 1893.

Chem. Soc. Jour., lxiii, 1136, 1893. **Chem. Soc. Jour., xxxiii, 189, 1878.

I have made a large number of crops of the compound, all of which agreed with Johnson's description in forming rectangular crystals of a black color having a marked brassy luster upon four of the six faces, and occurring usually in intergrown groups of nearly square, flat plates. In preparing these products the conditions were varied considerably. As a startingpoint 30 g. of potassium iodide and 50 g. of iodine were invariably used. These amounts give a slight excess of iodine over the proportion required for potassium triiodide. From 40 to 100 g. of crystallized lead acetate were used, and it was found that beyond these limits the preparation was unsuccessful. The solvent varied from absolute alcohol, diluted only with the water of crystallization of the lead acetate, to alcohol diluted with one-half its volume of water. Several crops

were prepared in the presence of glacial acetic acid, and a volume of this amounting to of the total liquid (20) was used with success. The total volume of solvent varied from 200 to 500, the larger amounts being used when it was not expected to obtain the product by simple cooling. It was customary to dissolve the potassium iodide and iodine in about one-half of the solvent to be used and the lead acetate in the remainder. The solutions were sometimes mixed boiling hot, while at other times a lower temperature was employed. A precipitate, evidently consisting chiefly of lead iodide, was always produced by mixing the two liquids, but its quantity was usually small. The effect of the presence of iodine in preventing the precipitation of lead iodide to a great extent is very remarkable. The solutions were filtered, sometimes while hot, sometimes after a longer or shorter period. The products obtained by cooling formed coherent crusts composed of very small, intergrown crystals, while by evaporation over sulphuric acid much larger isolated crystals, or groups of crystals were deposited. All the analyses given below were made upon crops obtained by evaporation, except in one instance. Two partial analyses of products made by cooling are not included in the list, because the results varied rather widely from each other and from the results obtained with the products of evaporations. The omitted results differed still more from Johnson's analysis than the others. Two or three successive crops were often obtained by evaporating a single solution, and the twelve products, analyses of which are given, represent six different original solutions. The products were well crystallized and most of them seemed entirely satisfactory in regard to purity. They were all examined microscopically, and as far as could be judged from the appearance of an opaque substance, no impurities were present. The samples for analysis were very carefully pressed upon filter-paper in order to remove the mother-liquor. The salt is practically stable in the air, so that decomposition was not to be feared during the drying operation.