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But with regard to the marine admits fp. grav. is to be invefti- 

 gated according to the ordinary mathematical rules. 



Problem 3d. 



To find how much water muft be added to 100 parts of an 

 acid liquor of a given fp. grav. to bring it down to another lower 

 given fp. grav. 



ift. Find by the table the quantities of acid and water in 100 



parts of each of the acid liquors refpedively, each being fuppofed 



to be in the table, let the quantity of water in the denfer be W, 



and the quantity of acid = A, let the quantity of water in the lefs 



denfe = w, and the quantity of acid = a, and the quantity of 



water to be added to 100 parts of the denfer = m 



then W + w muft be to A as w to a 



And 'Wa + am = A'w. And a m = A w — W a. 



. , A u) — W a 



And m = 



a 



Problem 4th. 



Given weights of a or more acid liquors of different fp. gravities 

 being mixed, to find the quantity of real acid in xoo parts of the 

 mixt liquor and its fp. grav. 



Find 



