618 ANNUAL REPORT OF THE Off. Doc. 



sarora Moimiaiu, one mile south of Van Dyke, Juniata eouuty, 99 

 per cent, silica; South Mountain, two miles south of Boiling 

 Springs, Cumberland county, 99.03 per cent, silica, and same range 

 of mountains two miles northwest of Mont Alto, 98.82 per cent, 

 silica. In every instance the sand or sand rock is in very large 

 body, and all the constituents other than silica contain a minimum 

 of deleterious substances. It is doubtful if another state in the 

 Union has so many large deposits of first grade silicates. 



Practical examination has shown that any of these sands will, 

 in sufficient body, thoroughly purify any water, no matter how com- 

 pletely impregnated with disease-breeding germs. Why any other 

 method of filtration should be thought of, much less adopted, in 

 Pennsylvania is beyond my ability to state. 



BEST SAND FOR MORTAR AND PLASTERING. 



It has also been demonstrated that plastering made of these silica 

 sands, and with a good quality of Pennsylvania-made lime, does not 

 require hair of any kind in the mixture. With first grade silica 

 sand from any of the localities mentioned, and our best lime, there 

 is no cracking of the plastering, there is an extraordinary adherence 

 to the lath, and there are no disease-breeding germs in the mass. 

 Then the plastering is so nearly a snow white that whitewashing is 

 uuuecessarv. Furthermore, mortar made of the materials men- 

 tioned make a brick wall almost as solid and enduring as if the 

 whole wall were of one brick. The samples exhibited herewith are 

 manifestly ample proof of what has here been stated. 



LIME AND LIMESTONE. 



While the lim(?stones of the Commonwealth have received more 

 than usual attention during the past five years, the subject of their 

 varieties and properties is not exhausted. It was my intention to 

 comi)lete, during the year just closed, a collection of average sam- 

 ples from every known deposit within our borders, but an unsual 

 number of calls to other states and territories prevented. The 

 work has been carried sufficiently far, however, to enable me to re- 

 port that we have at least 28 varieties, from the almost pure carbon- 

 ate of lime to the magnesite. When every variety has been ascer 

 tained, and a complete analysis of each made, we will then under- 

 stand more clearly why some burned limestone helps some soils in 

 so extraordinary a way, and other lime accomplishes so little. Tests 

 have jjroved that some limes, having marked percentages of mag- * 

 nesia, if allowed to thoroughly air-slake before using, will be bene- 

 ficial to soils where otherwise they will not. 



