ACRID PRINCIPLE OF HORSERADISH. HI 



seems therefore a fair conclusion, that the calorific ray, (pro- 

 ject* d from bodies artificially heated) after passing through 

 glass cannot he made to return again by any substance 

 placed on the opposite surface of the glass. In experiment 

 10th the black surface absorbs as 'much caloric as from its 

 nature it is qualified to do: the skreen has its temperature 

 raised a cerai-.i number of degrees, and becomes a source 

 of heat to the thermometer. But in experiment 11th some 

 of the calorific rays are immediately absorbed by the glass 

 surface; others pas; through the substance of the glass, but 

 are intercepted- by t ; j painted surface: and not being re- 

 turned through the Substance of the glass, they must assist 

 in raising the temperature of the whole skreen, which will 

 consequently become hotter in this than in the former expe- > 



riment. 



I trust, Sir, the experiments I have detailed will be suf- Radiant calori 



ficient to satisfy you, that radiant caloric, under favourable penetrates 



. , , , *» m some media 



circumstances, penetrates glass, and perhaps other diapha- without heat- 



nous media, independently of raising their temperature. I in g them* 



shall be glad to hear of their being repeated on a more ex* 



'tensive and varied plan ; and regret the want of leisure, 



which for the present prevents my farther prosecuting this 



interesting subject. 



I have the honour to be, Sir, 



Your most obedient servant, 



No. 99* Mcohon Street, Edinburgh, J. D. MAYCOCK. 

 April the 5th, 1810. 



vni. 



Oa the Acrid Principle of Horseradish : by Mr. Einhof*. 



WO pounds of the root of horseradish, dug up in the Horseradish 

 month of October, were rasped, and the pulp 'distilled on rootdistllled ' 



* AnnalesdeChim. vol. LXX, p. 185. Translated from Gehlen's 

 Journal. 



a water- 



