:\I.1X.UEIXG IX THEOPtY AXD PEACTICE. 



113 



It th.iis appears that in Paris tlie quantity of 

 nitrogen brouglit dovrn in rain is six times as great 

 -as it is in the open country of Alsace, a result no 

 doubt due to tlie aninionia evolved during th.e com- 

 bustion of fuel and to animal exhalations. To the 

 same cause the large quantity contained in the mois- 

 ture of the fogs of Paris may also be attributed. We 

 also observe that de-sv is much richer in plant-food 

 than rain, vrhich may serve to some extent to explain 

 its remarkably invigorating effect on vegetation. 



Again, in the valuable publication pre^viously re- 

 ferred to, are given the following analyses of rain, 

 dew, and hoar-frost, made by Dr. PranMand from 

 samples collected at Eothamsted, Hertfordshire : — 



T.IBLE SHOWING THE ^L^XIMUM, ]MlXIML'M, -IND 

 Mea>" A2,I0rNTS OF CERTAIX CoXSTITL'EXTS EN" 

 SlXTY-XIXE S.i3IPLES OE E.ilX-WATER IX PaETS 

 PER ]MlLLIOX. 



Highest proportion 

 Lowest proportion 

 Mean, 69 samples 



Nitrogen as 



S5-8 3-7-2!o-6r!i-2'^0-44 'l 



6-2'0-21 " -.1 i> 



33-li0-90 1- : - - 'J 



I ! 



94 16" 



131 0- 



" 16-0 



0-0 



1 47 



Turning to the analyses of dew and hoar-frost, the 

 samples examined embraced many distinct deposits : — 

 Table snowEs^a the ]\Iaximem, Miximim, and 



Me.\X AilOrXTS OF CERTAIX COXSTITEEXTS EX 



Seven Samples of Dew and Hoar-frost en- 

 Parts PER Million. 

























Nitrogen a 



s 



















2 



M 

















© 













— p 



B 



1 





I 



O 



ol 



5 



To 

 Nitre 



3 



M 





















Highest proportion . 



80 



4-cO 



_ 

 1-96 



2-3l'0-50 



4-55 



_ 



8-0 



25-0 



Lowest proportion 



26 4 



1-95 



0-26 



l-07,0-28 



1-63 



3-5 



13-0 



Mean, 7 sampks . 



48-7 



2-64 



076 



1-63 0-40+ 



2-79 



5-3 



19-0 



These small deposits condensed from the lower 

 stratum of the atmosphere contain on an average 

 three or four times the amount of organic carbon, 

 organic nitrogen, ammonia, and nitric acid, found in 

 heavier falls of rain-water. 



The total quantity of solid matter and the amount 

 of chlorine and sulphuric acid is also larger. 



* By "hardness" is imderstood the total iime and mag- 

 nesia in a water, expressed in parts of carhonnte of cal- 

 cinm. t The mean of thirty-four analyses only. 



t The mean of foiu- analyses only. 



Arranging the analyses of the Eothamsted rain- 

 waters, according to the quantity of the rainfall 

 and according to the various seasons of the year, we 

 obtain the following valuable results : — 



Table showing the Average Amoext of Xitrogen 

 as Ammonia in Monthly Eainfalls of diffe- 

 rent Quantity, in Summer, AVinter, and the 

 AVhole Year. 





Summer 

 Months. 



Winter 

 Months. 



Whole 

 Tear. 



Groups fif 

 Eainiall. 







Nitro- 



stn as 

 Ammo- 

 nia. 





Nitro- 1 

 gen as 

 Ammo- 

 nia, 



II 



Xitro- 

 gen as 

 Ammo- 

 nia. 

































































£ 





Below 1 inch 



1 to 2 inclics 



2 to 3 inches 



3 to 4 inches 

 Above 4 ins. 



2 



4 

 5 



m. 



0- 87 -890 



1- 65 -527 



2- 23 -537 



3 - 02 -410 

 5-32 -287 



lb. 

 •175 

 •197 

 •272 

 •335 

 •346 



5 0-Sl 

 51-32 



3 2-59 

 8 3^44 



4 5^30 



-!— 



•75r 

 •4 -s 



•263 

 •206 



■137 : 7 0^83 

 -139 12 1-51 

 -163 ;10 2-34 

 -205 '12 3-50 

 •247:1 9 5 •SI 



— L' — 



•792 

 -50o 

 •451 

 •314 

 •251 



•148 

 •173 

 •239 

 •248 

 •3(2 





25 



2-80 



•423 





25 2-69 



•296 



-180 50 2-74 



1 



-361 



-224 



The gradual decrease in the proportion of ammo- 

 nia per million of rain, as the rainfall of the month 

 becomes gi-eater, is plainly shown by these figures ; 

 the quantity of ammonia brought clown 'pev acre, 

 nevertheless, rises with each increase in the quantity 

 of rainfall ; but, taking the figures for the whole 

 year, it requires the rainfall to be increased about 

 six-fold in order to double the quantity of ammonia 

 contributed to an acre of land. 



Determinations of chlorine in monthly mixtures of 

 rain-water have been carried out in the Eothamsted 

 Laboratory since June, 1877. In the next table the 

 determinations in seventy-two monthly rainfalls are 

 grouped according to the amount of the rainfall and 

 to the season of the year : — 



Table showing the Average Amount of Chlorine 

 IN Monthly Eainfalls of different Quantity, 

 in Summer, Winter, and the A\'hole Year, 



Groups of 

 Rainfall. 



Summer 

 Months. 



Winter 

 Months. 



m. 



lb 

 0^65 



Below 1 inch! 3 ©•8:} 3^58 

 lto2 inches'lO 1-56 1^74 O^ei! 



2 to 3 inches 9 2-30;f40 i>73 



3 to 4 inches 5 3-55 1'25 1-01 

 Above 4 ins. 9 5-26 O^Sl 0-96 



Chlo- 

 rine. 



Whole 

 Tear. 



Chlo- 

 rine. 



ID 



'0^S15^76 

 9 1^52 3^46 



7 2-o9:2-65|l-5 



8 3-44 2-82:2-21 



lb. ! 

 1-06 



I in. I lb, 

 9 0-Sl 5^04 0^92 

 19 1^54 2-55 0-89 

 16 2-43 1-98 1-09 

 13 3-4^ 2-20 1-74 



•15,2-2o:2-c9 15 5-22 1-37 1-61 



3 1-21 0-79 36 2^64 2-S4 1-70 



I I 



1-90 1-2 i 



56 



