बेफोर गलिहोग्राफोरखौ बाहायथियाव लाबोनायनि सिगां सालफारनि एसिदजों उनजाथाय जाहोनानै गोगो थाथायाव दिहुनना लायो ।
Before using these solvents they are treated with sulfuric acid and obtained in pure form .