Memory 2 - preparation of dilute sulphuric acid! Friends, I want to share another experience with you. As a part of my research, I did a number of practicals but I remember a few things very vividly. One such work is the way we prepared dilute sulphuric Acid. I want to describe this to you. Myself, Dr. A.Annapurna and Mr. Kondaiah, we all worked under Prof. V. Subba Rao, for our Ph.D degrees, in the period of 1980s. At that time we all worked on the preparation of microspheres with gelatin and then complexing them with formaldehyde to slow down the release of the drug. In this work, dilute sulphuric acid was needed. This was the procedure we followed. We used to go to our sink and block the hole in the sink with a piece of cloth and fill it with water, so that the sink became a water bath. Then we used to put a glass vessel, whose glass thickness was nearly half inch, in this artificial water bath. Then we used to put the water necessary for the solution, in the glass vessel. We used to take the concentrated sulphuric acid into a thick beaker. From the thick beaker the sulphuric acid was poured into a measuring cylinder and necessary volume was measured. From the measuring cylinder the sulphuric acid was poured into the glass vessel, a few drops at a time and stirred well with a glass rod. Every time we added the acid, heat would be generated and we would leave some time for the dissipation of the heat into the water in the sink. After adding half the amount, we would carefully remove the glass vessel and empty the sink, and put the cloth again and fill it again with water. Then we would put the vessel back into the water bath again and add the sulphuric acid again and stir again. The entire procedure was done slowly. All the acid is not to be added at the same time as the reaction is highly exothermic. We used to spend nearly two hours in the evening for this work. Please remember that exhothermic reactions are to be handled with care. Laboratory work requires patience and understanding. Concept and principle must be understood before proceeding to the actual bench work.