278 CHEMICAL DEPARTMENT. 



sending samples for Analysis which had not been selected w ith 

 sufficient care, and were afterwards found not to represent the 

 average composition of the substance, it is particularly re- 

 quested that the following instructions may be attended to as 

 closely as circumstances will permit : — 



INSTRUCTIONS FOR SELECTING SAMPLES FOR ANALYSIS. 



Manures. — A large double handful of the Manure should be 

 taken from each of at least five or six different bags ; and if any 

 lumps are found in it, a due proportion of these should also be 

 taken. The whole being laid on a large sheet of paper, should 

 be carefully mixed by rubbing with the hand, the lumps being 

 broken down and mixed as uniformly as possible with the 

 powdery part. If this mixture be carefully made, a quantity of 

 it not exceeding two ounces will suffice for the analysis. It 

 should be folded up in tinfoil to prevent its becoming dry. In 

 default of tinfoil, the sample may be wrapped in double folds of 

 strong writing paper. Should the manure contain stones, or be 

 very moist, or should any difficulty be experienced in making a 

 uniform mixture, it is desirable that tiuo or three pounds should 

 be sent. 



Soils. — In selecting Soils for analysis, five or six spadefuls 

 should be taken from different parts of the field, and after being 

 spread out in a thin layer for several days to dry, should be put 

 two or three times through a fine sieve, so as to insure uniform 

 mixture. For a complete analysis, not less than two pounds 

 should be sent ; for a partial analysis, three or four ounces 

 will be sufficient. 



Waters. — For the complete analysis of a Water, from two'to 

 three gallons are required ; for the determination of the amount 

 of salts in solution, and lime thrown down by boiling, tvjo quarts 

 will suffice. A well water may be selected at any time ; but 

 the water of a spring or running stream should be taken in dry 

 weather. The jars or bottles in which they are sent must be 

 tightly corked and sealed. In the analysis of a miner? 1 water, 

 it may sometimes be desirable to determine the amount of gases 

 held in solution ; in which case certain precautions must be ob- 

 served which require the presence of a chemist at the spring. 



Limestones, Clays, Ironstones, &c. — If the bed of any of these 

 substances of which the analysis is required be very uniform in 

 appearance, a piece of two or three ounces weight taken from 

 any part of it will be enough for analysis ; but in all cases it is 

 better to send three or four chips from different parts of its thick- 

 ness. Sometimes where the characters of different parts of the 

 bed vary much, separate analyses of these portions may be 

 requisite, in which case two ounces of each may be sent. 



