340 DR. BENCE JONES ON THE VARIATIONS IN 



about two drachms of sulphate of magnesia in the morning, which did not act on the 

 bowels; at 12 beef-tea and bread. 



Earthy phosphates. Spec. gr. 



3 o'clock 2-99 per 1000 urine 1027'6 



A second experiment with the same urine, at the same time, gave nearly the same 



result ; the alkaline phosphates were only 1*45 per 1000 urine, specific gravity 1027*6. 



(24.) Another patient of Dr. Seymour's in St. George's Hospital, who had taken 



senna and salts in the morning, with beef-tea and arrow-root for dinner, gave 



Earthy phosphates. Spec. gr. 



2-93 per 1000 urine 1026'2 



The quantity of sulphuric acid present in this urine 



=3*21 per 1000 urine, specific gravity 1026*2 

 The amount given by Becquerel is = '95 1018'9 



The quantity stated by Becquerel is however below the average. 



From these experiments, 30 grains of dry sulphate of magnesia in an ounce and a 

 half of water produced no, or very little, effect in two hours. In four hours and a 

 quarter the effect was distinctly visible. 40 grains in two ounces and a half of water 

 produced a visible effect in two hours and a quarter, and a still more marked effect in 

 four hours and three quarters. The effect continued to be perceptible for 9f hours 

 after the medicine was taken. 



As compared with the previous experiments, though the quantity taken appears to 

 have been more, the effects seem not to have been so strongly marked ; but in fact 

 less of the base was taken in the last than in the previous set of experiments, for 

 30 grains of chloride of calcium are equivalent to 15*1 grains of lime, 

 40 grains of sulphate of magnesia are equivalent to 13*6 grains of magnesia. 

 As sulphate of magnesia is one cause of increase in the amount of earthy phosphates 

 precipitated by ammonia, and as this salt also interferes in analyses regarding the 

 quantity of sulphuric acid which is thrown out of the system, any means of knowing 

 when it has been given as a medicine may be valuable. Most frequently it is pre- 

 scribed with infusion of senna, which communicates a greenish yellow colour to the 

 urine. This colouring matter, whether it has passed through the system or not, I 

 find has the property of becoming of a deep red on the addition of an excess of any 

 alkali, though it is most bright with ammonia. The red colour disappears again on 

 neutralizing the alkali by an acid. It has a strong affinity for phosphate of lime. If 

 rhubarb is taken, a less bright colour is given by the same reagents. I have lately 

 found that Sir E. Home in some of his experiments on absorption used the reaction 

 of potash on tincture of rhubarb because it is so remarkable*. 



(25.) Breakfast as before. 45 grains of dry magnesia taken at 10 o'clock. It had 

 no action at all on the bowels. 



* Philosophical Transactions, 1808, p. 45. According to the researches of Schlossbeegek, this reaction is 

 caused by chrysophanic acid which exists in the rhubarb.— Annalen der Chemie, vol. 1. p. 214. 



