Show chemic duet falls imperceptibly hartley and ramage have re bently made a number 0 of dust from various sources by means ot the spectroscope dust from the collected either by itself or in hal snow sleet or rain exhibits a regular ity in composition not seen in other varieties of dust it contains alpar antly the same proportions of iron nickel calcium copper potassium and sodium collected and described three different kinds of dust one consisted of diatoms and another of and apparently tel sand both being obtained from the surface of the ice in greenland the third variety was composed of sooty looking particles containing elements invariably associated with iron me teon ties metallic cobalt nickel car bon silicon and phosphorus he there fore concluded that it was meteoric matter showered down upon the earth and that cosmic dust is falling imper and continually volcanic dust contains lime and magnesia and hows the spectra of the alkali metals flue dust contains larger proportions of lead silver and copper than ordinary dust or coal ashes in it are also found nickel and manganese as well as notable quant ties of the rare metals gallium indium and thai hum |