XXV 



Thus to convert ioo° F. to centigrade — 



100—32 C ^ 



= - ■ ■ C = 37.7 



9 5 J/ / 



2. Formula for dilution of Solutions.— The number of parts 



required to dilute from one part of a solution of strength x per 



cent, to another strength y per cent, is- - i 



y 



Thus, to dilute a solution from 20 per cent, to 5 per cent., add 

 to each volume of solution H2 _ i = 3 of the diluting fluid. 



3. Approximate Values: — 



I cubic centimetre = 17 minim. i minim = '059 c.c. 



100 ,, =3 ounces, 4 drachms, 20 minims. 



I drachm = 3-55 c.c. 

 1000 cubic centimetres = 176 pints. 1 fluid ounce — 



28-4 c.c. 



4 litres = 7 pints, i pint = 568 c.c. 



I gramnie = i5|ths grains (avoirdupois). i grain 

 (avoirdupois) = '0648 grammes. 



I kilogramme = 2 pounds, 3 ounces, iig'S grains (avoir- 

 dupois). I drachm = 177 grammes. 



5 kilogrammes = 11 pounds, i oz. = 28'35 grammes. 

 I grain apothecaries' = '0648 grammes. 



I drachm apothecaries' 5 = 3'88 grammes. 

 I ounce apothecaries' § =^ 31' i grammes. 

 I5'4 grains apothecaries' = i gramme. 



4. I millimetre = '039 (-jV) inches. i inch = 2'5 



centimetres. 



I centimetre = -39 (J) inches. idVt inch = "0253 milli- 

 metres. 



I metre = 3'28 feet, ris^ inch = i millimetre. 



TTi'inr millimetre (/x) = '00004 inches. 



5/ot = Www inch. l/a = tdsVos inches. 



5. TT = 3'i4i59- 



Circumference of a circle = 2 Try = Trd. 

 Area of circle = Tcr^. 



LIST OF APPARATUS 



^ s. d. 



1. A Beck microscope, including oil immersion, 1^1 13 10 o 



2. Glass slides, I 3x1, ground edges, per gross 036 



■f Slides and coverglasses should be kept in spirit or alcohol to prevent their 

 becorning opaque, as only too frequently occurs in the tropics. 



