OF ARTS AND SCIENCES. 27 



of their decomposition may throw additional light upon the structure 

 of uric aci(i. 



A few preliminary experiments convinced me that the compounds in 

 the methyl series could be much more conveniently made than those 

 of the ethyl or benzyl. I tlierefore began with the methyl ethers, and 

 this paper gives tl^^ results I have obtained in the study of the first of 

 these. 



Methyhiric acid, C-H3(CH3)N^03. 



Methyluric acid may readily be prepared by the action of methyl 

 iodide upon monoplurabic urate. The metathesis takes place slowly 

 at 110°-130°, rapidly between 160° and 165°. The dry lead salt 

 mixed with methyl iodide in molecular proportions, enough ether being 

 added to keep the mixture fluid, is heated in sealed tubes for eighteen 

 hours at 165°. After tlie evaporation of the ether, the product of the 

 reaction is boiled with water, and the solution filtered from the un- 

 altered plumbic urate. The lead is then precipitated with hydric 

 sulpliide, and the plumbic sulphide filtered off boiling hot. The filtrate 

 deposits, on cooling, meihyluric acid in small crystals. Tliese are 

 dissolved in dilute potassic hydrate, the solution boiled for a ^evf 

 minutes, reprecipitated by hydrochloric acid, and recr}stallized from 

 boiling water. The yield is about 60 f^ of the amount theoretically 

 required by the lead salt which enters into the reaction. 220 grms. 

 plumbic urate gave 54 grms. methyluric acid, and 89 grms. of unaltered 

 lead salt. Afterwards, in working up the recovered lead salt, which 

 was much more compact in form than the salt originally employed, I 

 found the decomposition almost complete. In this case 100 grms. lead 

 salt gave me 41 grms. methyluric acid. A portion of the uric acid is 

 completely decomposed, and is found as ammonium salt in the mother 

 liquors and the crude product. I attempted to increase the yield by 

 employing anhydrous ether in the place of common ether. Although 

 no ammonium compounds were then formed, a much smaller percent- 

 age of the lead salt entered into reaction. Longer heating at a .ewer 

 temperature did not increase the yield, inasmuch as a larger quantity 

 of dimethyl ether was then formed. The amount of dimethyl ether 

 formed by heating to 16.)° is small; and as it is much more soluble in 

 water than the monomethyl ether, it may readily be removed by re- 

 crystallization. 



Methyluric acid crystallizes in small clear flat prisms, apparently of 

 the triraetric system, the crystals being often pointed at either end. 

 By slow cooling of a dilute solution, these crystals sometimes reach a 



