The Phosphates of America. 165 



WEIGHTS AND MEASURES OF THE METRICAL SYSTEM. 



Weights. 



1 milligramme = .001 gramme. 



1 centigramme = .01 gramme. 



1 decigramme = .1 gramme. 



1 gramme = weight of a cubic centimetre of water at 4 C. 



1 decagramme - 10.000 grammes. 



1 hectogramme = 100.000 grammes. 



1 kilogramme = 1000.000 grammes. 



Measures of Capacity. 

 1 millilitre = 1 cubic centimetre, or the measure of 1 gramme of 



water. 



1 centilitre = 10 cubic cent. 

 1 decilitre = 100 cubic cent. 

 1 litre = 1000 cubic cent. 



Measures of Length. 

 1 millimetre = .001 metre. 

 1 centimetre = .01 metre. 

 1 decimetre = .1 metre. 

 1 metre = the ten-millionth part of a quarter of the earth's meridian. 



STOCHIOMETRY, OR CHEMICAL CALCULATIONS. 



Conversion of Thermometer Degrees. 



C. to R., multiply by 4 and divide by 5. 



"C. to F., multiply by 9, divide by 5, then add 32. 



R. to C., multiply by 5 and divide by 4. 



R. to F., multiply by 9, divide by 4, then add 32. 



F. to R., first subtract 32, then multiply by 4 and divide by 9. 



F. to C., first subtract 32, then multiply by 5 and divide by 9. 



To Find the Percentage Composition having the Formula Given. 

 Find the molecular weight from the formula, then 



Molecular weight Weight of constituent in a molecule. 

 100 Percentage of constituent. 



Or, proceed thus : 



Multiply the atomic weight of the element by 1, 2, 3, etc., according 

 to the number of atoms of the element there are in the molecule ; multi- 

 ply the number thus obtained by 100 and divide by the molecular weight. 



To Find the Weight of any Element Contained in any Given Weight 

 of a Compound Substance. 



Molecular weight _ Weight of constituent in a molecule. 

 Given weight Required weight. 



Or, multiply the atomic weight of the element by 1, 2, 3, etc., accord- 

 ing to the number of atoms of the element there are in the molecule ; 

 multiply the number thus obtained by the given weight and divide by 

 the molecular weight. 



