of solid matter held in suspension in the water of the Rhine, and requested that a similar process should be followed. Dr. Abbott's account of his experiment, contained in a letter to me dated Cairo the 12th of December 1850, is as follows:—"I began your experiment on the 1st of October, and on that day took an imperial gallon of water from the Nile at the depth of 20 feet, and at that part of the river opposite the Transit Wharf at Boulac. The current is there very strong, and the water is not likely to have any of the dirt or filth that might possibly be mixed with it lower down, where a large number of boats are collected. I took one gallon of water daily for ten days, which I put into an earthen filter, and left covered, until it became perfectly dry; and then put it into a paper and kept it until a week ago, when I weighed it and found the quantity to be 181 drachms apothecaries weight (1110 grains). I am now endeavouring to dry it in a cake, or rather to bake it in the form of a small brick to send to you."
I weighed the little brick sent to me accurately on the 11th of May 1851, and found it to be 1106 grains, so that the solid matter held in suspension is 110⋅6 grains in an imperial gallon. An analysis of this solid matter was made at the Royal College of Chemistry in London, by Mr. Brazier,under the superintendence of Dr. Hofmann, and yielded the following results:—
- Sesquioxide of iron18⋅43
- Sesquioxide of alumina8⋅76
- Carbonate of lime4⋅19
- Sulphate of lime0⋅75
- Chloride of sodium0⋅04
- Organic matter9⋅03
This hardened mass, when moistened, kneaded into a clay.
In future references to this specimen I distinguish it by the letter A.
B. A specimen of Nile sediment from the lower part of the Delta, sent to me by Mr. Murray.—It was collected at Damanhour, about six miles and a half from the left bank of the Rosetta branch, from a branch canal which connects the Nile with the Mahmudieh Canal near Bastié, and was a part of the sediment deposited by the inundation of 1849. This deposit is carefully collected on account of its ferti-
- Edinburgh New Philosophical Journal, January 1835.
- That the accuracy of the analyses might be relied on, I requested and obtained the aid of my distinguished friend Dr. Hofmann, who kindly undertook the superintendence of this and of the other analyses hereafter mentioned.