138 AGRICULTURAL REPORT. 



Certain insects appear abroad only at certain hours of tlie evening or 

 nigbt. For example, many motbs fly only from eigbt o'clock to balf 

 past nine or ten ; anotber genus or species tben takes its place until 

 eleven, and so on until tbe morning dawns. All tbese apparently very 

 insignificant details ougbt to be carefully studied and noted down, so 

 as to know exactly bow and wlien we may expect to meet with certain 

 insects. In short, the duty of tbe practical entomologist should be to 

 inquire into the minutest detail of the lives and habits of the insects he 

 has to deal with, as much as the physician does of the diagnosis of 

 diseases, so as to know exactly when, where, and how they may be 

 combated to the greatest advantage. 



TOWNEND GLOVER. 



Hon. Fred'iv Watts, 



Commissioner of Agricidtiire. 



REPORT OF THE CHEMIST. 



The report of 1871 embraced the work of the laboratory up to the 

 15th of May ; since that time we have been engaged in the analysis of 

 natural fertilizers, as a specialty. The amount of miscellaneous business 

 is rapidly increasing, and interferes materially with the prosecution of 

 any special line of investigation, when the labor in both is required to 

 be performed by a single assistant. We present an abstract of our 

 work on 



NATURAL FERTILIZERS. 



A specimen of calcareous tufa, from Abingdon, Virginia, presented by 

 Hon. John W. Johnson, is composed of— 



Carbonate of lime 94. 750 



Silica and alumina 5. 221 



Loss - 029 



100. 000 



Shell-marl from Newbern, N. C, presented by J. P. Dillingham, is 

 comjiosed ol^ — 



Water, determined at 100° C 0.G50 



Organic matter ^ , 2. 850 



Peroxide of iron and alumina 4.001 



Phosphoric acid 0.099 



Lime 13. 451 



Potassa ..-■ 0.331 



Carbonic acid 10. 600 



Silica 68.018 



100. 000 



Marl from Glymont, Maryland, presented by Leonard Marbury, 

 gives, on analysis — 



Water, determined at 100^ C .3.840 



Organic matter 2. 200 



Phosiiliate of lime, (tribasic) 4. 413 



Carbonate of lime 19. 639 



Carbonate of magnesia .* 4. 238 



Peroxide of iron aud alumina 6. 859 



Silica 58.990 



Potassa 0. 725 



Chlorine 0.09G 



100. 000 



