یہ اقبال کی دوسری نثری کتاب ہے۔ اسے لندن کی لوزاک اینڈ کمپنی نے 1908ء میں شائع کیا۔ یہ اقبال کا تحقیقی مقالہ ہے ۔ اقبال نے اس پر میونخ یونیورسٹی سے پی ایچ ڈی کی ڈگری حاصل کی تھی۔ اس پی ایچ ڈی کے لیے اقبال نے جرمن زبان بھی سیکھی مقالہ لکھ کر داخل کیا تو اسے غیر معمولی قرار دیا گیا اور اس پر بہت عمدہ تاثرات لکھے گئے۔اس کا اردو ترجمہ 1927ء میں حیدر آباد سے شائع ہوا۔ اقبال اس اردو اشاعت کے خواہاں نہ تھے۔
Islam is considered to be the religion of nature due to its originality and suitability to human nature for all times or centuries. It continues to be successful in the developed world, and elsewhere, because its call is in accordance with the fitrah or natural inclinations of mankind. Allah, subhanahu wata'aala, is the creator of mankind and therefore knows his nature more intricately than mankind himself. Allah has therefore chosen for us a religion best suited to the nature of mankind, a religion that goes neither to the extremes of hardship nor of laxity, but instead provides a middle path; in other words, a religion of ease. Islam does not lay on people tasks that they cannot do or they will have difficulty in doing. Whenever, there is any difficulty performing any religious obligation faced by Muslims, they have provided an element of ease and comfort. In this regard, the focus of this paper is to throw light on the notion of ease and leniency of Islam.
In this work the corrosion process occurring on the surface of copper and four types of brasses i.e. CuZnAl, CuZnSn, CuZnPb and CuZnMn was investigated using elec- trochemical techniques. Electrochemical Impedance Spectroscopy (EIS), Cyclic Volt- ammetry (CV) and Potentiodynamic methods were the three techniques used. As the corrosion process is pH dependant, the investigations were carried out at three pH - slightly acidic (6.4), slightly alkaline (8.4) and strongly alkaline (10.4) in borate buffer. It was observed that the variation in pH altered the mechanism and also the rate of corrosion. In case of the four types of brasses it was observed that dopant in the brasses affected the corrosion rate i.e. CuZnMn had the highest corrosion rate (CR) of 0.019mm/yr and CuZnAl had the least CR of 0.009mm/yr in strongly alkaline medium. However the corrosion rate of all the brasses was found to be smaller than that of pure Cu (0.132 mm/yr). The same trend was observed for slightly alkaline and acidic pH. The corrosion phenomenon was also studied in the presence of azoles which inhibited the process of corrosion. The five azoles were benzotriazole (BTA), mercaptobenzothiazole (MBT), benzimidazole (BIMD), mercaptobenzimidazole (MBIMD) and thiadiazole (TDA As the inhibitory action of the five azoles was attributed to their adsorption on the sur- face of Cu and brasses, the adsorption isotherms were plotted and thermodynamic pa- rameters for the adsorption process were calculated. High negative value of DG indi- cated highly spontaneous process of chemisorption. Inhibitor efficiencies for the five azoles were also calculated from CV, EIS, and PD methods and it was observed that MBT and TDA were better inhibitors due to the presence of S atom. The relative in- hibitor efficiency (I.E) was found to be in the order MBT > TDA > MBIMD >BIMD > BTA. The effect of pH and concentration of azole on its corrosion inhibitory action was also investigated. It was observed that azoles had the highest I.E values at pH = 8.4. Impedance spectra were characterized in terms of the charge transfer resistance and transport of copper ions through the oxide layer. The results indicate that the surface layer is of dielectric nature, and its protection increases with increasing inhibitor con- centration with a maximum value at pH 8.4. The corrosion process was also studied in the presence of halide ions (F-, Cl-, Br- and I-) which are known to decrease corrosion resistance at the three pH. The I- ion was found to be the most aggressive halide ion with different mechanism of corrosion. The relative order of aggressiveness of the halide ion was I-> Br- >Cl- > F-. This order was confirmed from the experimental results obtained from the three methods i.e. CV, EIS and potentiodynamic measurements. DFT calculation with 6-31 G* basis set were carried out on the five azoles and the theoretical parameters were correlated with inhibitor efficiencies. Keywords: copper, brass, adsorption isotherms, borate buffer, azole corrosion inhibi- tors, halide ions, electrochemical impedance spectroscopy, cyclic voltammetry.