62 DR DAVY ON THE RAIN-FALL IN THE LAKE-DISTRICT. 



during part of the preceding day and night — that is, in somewhat less than twenty- 

 four hours. The wind was mostly S.W. and strong, and that there was a gale at 

 sea was denoted by the presence of gulls in the valley. The temperature of the 

 rain-water, as poured from its receptacle, was 48^ The effect of nitrate of silver 

 on it, employed in the usual manner, was moderate. Two measures — that is 50 

 grs. — evaporated, left a well-marked stain, in which, under the microscope, were 

 to be seen a few cubic crystals, a slight arborescent crystallization, and many 

 granules. Of the whole 4* 83 inches, a portion equal to -23 inch was used in these 

 preliminary trials. The remainder, viz., 4 60 inches, were divided into two por- 

 tions, — a larger, 330 inches, equal to about 578 pints ; and a smaller, 1-30 inch, 

 equal to about 2-46 pints. The first was evaporated without any addition. To 

 the second, before evaporation, a drop of muriatic acid was added. 



The first was reduced to 356 grs. This was found to be of specific gravity 

 10-017. A part of it was expended in test-trials, the results of which were the 

 following : — A slight acid reaction, and an indication, using appropriate tests, of the 

 presence of muriatic and sulphuric acid, of soda, lime, and magnesia, with a trace 

 of alumina, phosphoric acid, and copper. The second was reduced to 200 grs. 

 Evaporated to dryness in a weighed capsule, it yielded a residue of *45 grs., of 

 a light brown hue. Heated in a glass tube it became blackened, charred, and a 

 fine sublimate was condensed in the upper part of the tube ; this, seen under the 

 microscope, had a delicate crystalline appearance, like that of muriate of ammonia, 

 and had no alkaline reaction, until a few drops of liquor potassae were added, 

 when there was a decided production of ammonia, a fume appearing on the 

 approach of muriatic acid properly diluted, and a slip of litmus paper reddened, 

 recovering its blue colour when put into the tube. 



The smaller portion of the rain-water, that which slightly exceeded two 

 pints, to which the drop of muriatic acid had been added, was evaporated until 

 reduced to 94 grs. A drop or two of this, evaporated to dryness on a glass 

 slide, left a residue in which cubical crystals, like those of common salt, were 

 most numerous, intermixed with which were a few prisms like those of phosphate 

 of lime, a few tabular ones resembling those of sulphate of lime, and others like 

 muriate of ammonia in its crystallised state, and there were stellate and dagger- 

 like crystals amongst them. This smaller portion, so reduced, subjected to the 

 same tests and trials as the larger, afforded similar results, with the exception, 

 that there appeared to be more muriate of ammonia present, leading, of course, to 

 the conclusion, that the rain-water contained a little carbonate as well as muriate 

 of ammonia. After exposure to moist air, all the crystals described deliquesced, 

 with the exception of the plates and prisms, and those of a stellate form. 



Several other specimens of rain-water, these varying in volume from one to 

 two and three pints, have been evaporated, until, like the preceding, they were 

 reduced to a small quantity and then tested. The results were chiefly the fol- 



