2 42 Gases, Acids, Salts, ^c. 



efflorescence on the marly clay banks at the same place, 

 and tlie extensive efflorescence of epsom sahs in Lansing- 

 buriih, six miles north of this city, (Troy, N. Y.) have been 

 described by Dr. Beck and myself in our Ajiricultural Sur- 

 veys of Mr. Van Rensselaer's Manor. It is in a solid state, 

 attached to several of the secondary rocks, in situations de- 

 fended from rains by shelving layers ; as on the lias along 

 Flat creek, south of the Mf)hawk — in the east ledge near the 

 head of Cayuga lake, for three or four miles, in connexion 

 with sulphate of iron and a thin layer of coal — in Auburn, 

 in the base of a hill on the east bank of Owasco creek — at 

 Genessee Falls, &c. In every case we find iron pyrites and 

 magnesia in the rock to which it is attached. 



The two greatest localities hitherto observed in this dis- 

 trict, are those of Coeymans and Lansingburgh, before re- 

 ferred to. In both cases the incrustations of the salt form 

 on extensive banks of marly clay, when the season is dry ; 

 which incrustation is dissolved and washed away with the 

 first rain. At the Lansingburgh locality, which is on Judge 

 Hickock's farm, the bank is forty or fifty feet high, and about 

 as many rods in length. It is often seen after a long drought 

 with the whole face of the bank nearly covered with the 

 salt. The marly clay constituting the bank and producing 

 the salt, gives evidence of the presence of magnesia when 

 tests are applied. But I have never ascertained the propor- 

 tion of it, nor how it is combined. Iron pyrites is found in 

 it in very minute grains, and in variable proportions. 



7. Muriate of Lime. 



This is another case of a common salt, omitted in systems 

 of mineralogy. I have not been able to find any notice of 

 this salt, as a mineral, in any English or French work ; al- 

 though it is certainly one of the most universal salts known. 

 On this account Dr. Emmonds, at my request, inserted it in 

 his Manual of Mineralogy, published at Albany, 1826. 



After the most diligent examinations, and inquiries, I have 

 not found a bed of marly clay which did not contain it. 

 Soak in pure water fifty pounds of dry or damp marly clay, 

 taken from near the lower side of a layer, let it settle, and 

 the clear supernatant liquid will always exhibit evidence of 

 the presence of this salt, when nitrate of silver and oxalate 

 of ammonia are applied to separate portions. All wells sunk 

 in marly clay furnish what is denominated hard water. This 



